18th INA Conference, Avignon, France, 2022, abstracts © 2022 International Nannoplankton Association
ISSN 1210-8049 Printed by The Sheridan Press, Hannover PA, USA

Convenors
LUC BEAUFORTCLARA BOLTONBAPTISTE SUCHÉRAS-MARX

Aix-Marseille University –– France

Organising Committee
LUC BEAUFORTFRANÇOISE CHALIÉCLARA BOLTONBAPTISTE SUCHÉRAS-MARX

THIBAULT DE GARIDEL-THORONYVES GALLYJEAN-CHARLES MAZUR

Aix-Marseille University –– France

Scientific Committee
BLANCA AUSINMICHAËL HERMOSOALICIA KAHN

University de Salamanca –– Spain

Université du Littoral –– France

Chevron ––USA

DENISE KULHANEKCHUANLIAN LIU

ALEX POULTON

Universität zu Kiel –– Germany

Tongji University –– China

Heriot-Watt University –– UK

MARIA TRIANTAPHYLLOUGIULIANA VILLA

Panepistímio Athinón –– Greece

Universitá di Pavia –– Italy

Conference Support
CAMILLE GODBILLOT

BLANDINE GODET

MAJD HABIB

Aix-Marseille University –– France

University of Lorraine –– France

Aix-Marseille University –– France

Fieldtrip Contributors
PAULINE COSTERPHILIPPE LÉONIDE

Luberon Regional Natural Park/UNESCO Global Geopark –– France

Aix-Marseille University –– France

ALEXIS LICHTTHIERRY TORTOSA

Aix-Marseille University –– France

Sainte-Victoire National Natural Reserve –– France

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Welcome to INA18!
28 August–3 September, 2022

Le Palais des Papes, Avignon

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Bienvenue à Avignon!
INA18 is happening after a one-year delay because of the COVID-19 pandemic. This year, travelling isagain permitted in many countries, and so meeting here in France is now possible. This meeting will be theperfect occasion for the nanno community to again enjoy in-person exchanges of our latest research andnannoplanktonic adventures. This meeting is taking place in a rare and beautiful Gothic palace dating fromthe 14th century, from where the popes of that time ruled over a Catholic Europe. This historical place will
provide the atmosphere for an enjoyable experience, while sharing our studies on eight main topics related
to nannofossils and coccolithophores, including their crystallography, geochemistry, evolution, ecology,
biostratigraphy, palaeoceanography, morphometry and taxonomy.
More than 100 participants are going to be gathered in the conference centre in the palace (with 110
registrations), coming from 25 countries, including Argentina (1), Austria (2), Brazil (1), Bulgaria (1), China(9), Colombia (1), Croatia (3), Denmark (1), France (19), Germany (7), Greece (1), India (1), Israel (1), Italy(15), Japan (2), Jordan (1), Philippines (1), Portugal (2), Romania (2), Spain (7), Sweden (4), Switzerland (1),Czech Republic (4), UK (10) and USA (13). INA18 will be showcasing our community’s research in 55 oralpresentations and 48 posters.
We are sincerely happy that you all made it here!
Luc Beaufort, Clara Bolton and Baptiste Suchéras-Marx
INA18 Convenors
Avignon 2022

INA18 Programme
Monday 29th August
9:00 – 9:20 – Opening ceremony, welcome andannouncements
Convenors: Luc Beaufort, Clara Bolton & Baptiste
Suchéras-Marx
Session 1 – Crystallography and geochemistry
Chairs: Marie-Pierre Aubry & Baptiste Suchéras-Marx
9:20 – 9:40
Young & Bown – The V/R model of heterococcolithbiomineralisation 30 years on: Unanswered questions andcontinuing relevance
9:40 – 10:00
Utsunomiya & Kogure – Morphological andcrystallographic variation in coccoliths of the
Umbilicosphaera (Calcidiscaceae) lineage
10:00 – 10:20
Chowdhury et al. – The mesostructural evolutionof Nannoconus via ptychographic X-ray computed
tomography

Coffee break
Session 1 (cont’d) – Crystallography and geochemistry
10:50 – 11:10
Godet et al. – Experimental diagenesis and quantitative
assessment of Discoaster overgrowth
11:10 – 11:30
Mutterlose et al. – Provenance analysis of historic mortars
and mortar-based materials: A micropalaeontologicalapproach
11:30 – 11:50
Falkenberg & Mutterlose – Burning experiments
on calcareous nannofossils: Contribution to a better
understanding of historic mortar production
11:50 – 12:10
Giuliana Villa & the INA Committee – Special event
Lunch break

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Session 1 (cont’d) – Crystallography and geochemistry
14:00 – 14:20
Bordiga et al. – Silicon in fossil and cultivated coccoliths
of Helicosphaera carteri: New insights from X-ray
ﬂuorescence and infrared spectroscopy analyses
14:20 – 14:40
Chin et al. – Isolating and analysing the coccolith-sized
fraction as a metric for diagenesis
14:40 – 15:00
Godbillot et al. – Isotopic response of Pleistocene
coccoliths to an ambient pCO2 change: A calibration
experiment
15:00 – 15:20
Le Guevel et al. – Oceanic temperature and pCO2
reconstruction during the Pliocene in the Caribbean Sea(ODP Site 999) using coccolith geochemistry

Session 2 (cont’d) – Evolution and ecology
10:50 – 11:10
Langer et al. – Distinct physiological responses of
Coccolithus braarudii life-cycle phases to light intensity
and nutrient availability
11:10 – 11:30
Suchéras-Marx et al. – Inﬂuence of coccolithogenesis on
coccolith size and distribution
11:30 – 11:50
Hagino et al. – Marine phytoplankton biogeography
before the recent global ocean warming
11:50 – 12:10
Sheward et al. – Poorly recognised diversity in PIC to
POC ratios underpins the role of coccolithophores in themarine carbon cycle
Lunch

15:20 – 17:20 – Poster session
17:20 – 18:20
Keynote by Rosalind E. M. Rickaby – Perturbing
coccolithophores: The past and future of Earth’s stabilisers
Tuesday 30th August
Session 2 – Evolution and ecology
Chairs: Camille Godbillot & Ian Probert
9:00 – 9:20
Filatov et al. – How do new phytoplankton species formin the open ocean?
9:20 – 9:40
Beaufort & Dauvier – Evolution of Gephyrocapsa
oceanica: Equatorial seasonality at play
9:40 – 10:00
Aubry – The heteromorphic haploid–diploid life-cycleof coccolithophores: Insights into genetic ﬁngerprinting,
adaptive morphology, phylogeny, and the origin andmaintenance of a complex cycle
10:00 – 10:20
Henderiks & Voje – Rates of phenotypic evolution incoccolithophores

Session 3 – Biostratigraphy
Chairs: Emanuela Mattioli & Giuliana Villa
14:00 – 14:20
Demangel et al. – Early evolution of calcareous
nannofossils in the Late Triassic in the Neo- and PalaeoTethys Oceans
14:20 – 14:40
Riﬂ & Holcová – Calcareous nannoplankton from theuppermost Triassic in the Southern Alps, Slovenia
14:40 – 15:00
Sheldon et al. – Improving characterisation of the tight
Lower Cretaceous marly chalk reservoir, Central North
Sea: A nannofossil biostratigraphic, sequence stratigraphic
and sedimentological approach
15:00 – 15:20
Kulhanek et al. – Cretaceous–Paleogene calcareous
nannofossils from International Ocean Discovery Program
Expedition 392 to the Agulhas Plateau, SW Indian Ocean
15:20 – 15:40
De Kaenel et al. – The Paleocene/Eocene boundary andemendation of the NP9/NP10 zonal boundary of Martini(1971)
Coffee break

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Session 3 (cont’d) – Biostratigraphy
16:20 – 16:40
Chira & Bindiu-Haitonic – Eocene calcareous
nannofossils from the Humor Basin (eastern Carpathians,
Romania): Biostratigraphy and palaeoenvironmental
reconstruction
16:40 – 17:00
Wang Xuejiao et al. – Regression of the Tethys Sea inCentral Asia in the Middle to Late Eocene: Evidence from
calcareous nannofossils in the western Tarim Basin, NW
China
17:00 – 17:20
Holcová et al. – Strontium isotope stratigraphy vs.
calcareous nannoplankton datums in an epicontinental
sea: A case study from the Miocene Paratethys
17:20 – 17:40
Vallejo Hincapié et al. – The Neogene Central Americanseaway17:40 – 18:00
Lozar et al. – The Lorca Basin revisited: How integrated
stratigraphy can help resolve long-standing controversies
18:30 –
External event at the Museum of Natural History (Requien
Museum): Opening of the nannofossil art exhibition by
Isabelle Rochemars

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Ashajara, northern Jordan, and their implications for thedepositional environment
Coffee break
Session 4 (cont’d) – Palaeoceanography
10:50 – 11:10
Lukić et al. – Mid-Eocene thermals record in the Istrian
Paleogene basin (Outer Dinarides, Croatia), Neotethys
11:10 – 11:30
Ma Ruigang et al. – Nutrient forcing on the Late Middle
Eocene to Early Oligocene (~40–31 Ma) evolution of thecoccolithophore Reticulofenestra (Order Isochrysidales)
11:30 – 11:50
Wang Yasu et al. – Evolution of Miocene
calcareous nannofossil assemblages as a response topalaeoceanographic changes in the northern South China
Sea
11:50 – 12:10
Mancini et al. – Oligo-monospeciﬁc assemblage of
calcareous nannoplankton in response to the Messinian
palaeoceanographic setting: Insights from the Monte dei
Corvi section (central Italy)
Lunch break
14:00 – 16:00 – Poster session

Wednesday 31st August
Session 4 – Palaeoceanography
Chairs: Clara Bolton & José-Abel Flores
9:00 – 9:20
Mattioli et al. – Weakening of the biological pump
induced by a nannoplankton crisis during the Early
Toarcian Oceanic Anoxic Event
9:20 – 9:40
Bettoni et al. – How did calcareous nannoplankton
respond to palaeoenvironmental-factor changes at low
and high latitudes across the Late Aptian–Early Albian
interval?
9:40 – 10:00
Pige et al. – New estimation of Late Paleocene calcareous
nannoplankton ﬂuxes at ODP Site 1209 (North Paciﬁc)
10:00 – 10:20
Alqudah et al. – Calcareous nannofossil assemblages
and geochemical analysis of Eocene oil shales from Wadi

16:00 – 18:00
Giuliana Villa, Emanuela Mattioli & the INA
Committee – INA business meeting
16:00 – 16:20
Young et al. – Nannotax: Bibliography project and otherupdates
20:00 –
Gala dinner, Palais des Papes
Thursday 1st September
Session 5 – Quaternary and modern ecology
Chairs: Alba González-Lanchas & Alyssa Peleo-Alampay
9:00 – 9:20
Sun et al. – Blooming coccolithophores identiﬁed in
the western Paciﬁc during the mid-Brunhes dissolution
interval

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9:20 – 9:40
Sarao & Kulhanek – Environmental factors inﬂuencing
calcareous nannofossil distribution over the past 96,000
years in the Panama Basin, eastern equatorial Paciﬁc
9:40 – 10:00
Johnson et al. – Extant coccolithophore distribution in the
Mediterranean Sea: A review
10:00 – 10:20
Millán et al. – The coccolithophore community of theSargasso Sea
Coffee break
Session 5 (cont’d) – Quaternary and modern ecology
10:50 – 11:10
Winter et al. – A high-resolution depth proﬁle ofcoccolithophores in oligotrophic waters of the North
Atlantic Gyre
11:10 – 11:30
Cachão – Calcareous nannoplankton as a useful tool incoastal dynamics and (palaeo)environments
11:30 – 11:50
Grelaud et al. – Coccolithophore ballasting effect onmarine microplastics export and accumulation
11:50 – 12:10
Jin et al. – Coccolithophore abundance, degree ofcalciﬁcation and their contribution to particulate inorganiccarbon in the South China Sea
Lunch
Session 6 – Morphometry and taxonomy
Chairs: Eric de Kaenel & Rosie Sheward
14:00 – 14:20
Su et al. – Late Quaternary coccolith weight variations in
the South China Sea and their environmental implications
14:20 – 14:40
Patil et al. – Emiliania huxleyi biometry and calciﬁcation
response to the Indian sector of the Southern Ocean
environmental gradients
14:40 – 15:00
Baumann & Strack – Occurrence and development ofEmiliania huxleyi morphotypes in the North Atlantic
Ocean during the last 290,000 years

15:00 – 15:20
González-Lanchas et al. – Calciﬁcation of theGephyrocapsa complex during the Mid-Brunhes Event
Coffee break
Session 6 (cont’d) – Morphometry and taxonomy
16:00 – 16:20
Erba et al. – Morphometric changes in the genus
Watznaueria in the Toarcian–Aalenian: Implications fortaxonomy, biostratigraphy and evolution
16:20 – 16:40
Archontikis et al. – Morpho-taxonomic reassessment of
the extant coccolithophores Ericiolus and Mercedesia
16:40 – 17:00
Varol & Bowman – New Middle Miocene genus
Olladiscoaster
17:00 – 17:20
Razmjooei & Thibault – Morphometric changes in two
Late Cretaceous calcareous nannofossil lineages support
diversiﬁcation fueled by long-term cooling
17:20 – 17:40
Howe – Ultrastructure and taxonomy of the Family
Fasciculithaceae
Poster session
Posters
Addante et al. – Coccolithophore distribution in water
samples from the Ebro Delta coastal area (Spain)
Alqudah et al. – Calcareous nannofossils from the Samuarea (Campanian), northern Jordan
An et al. – Primary production and assemblage
composition variations in the coccolithophores of the Gulf
of Papua during the past 150 ka
Anton&
Melinte-Dobrinescu–
Oligocene
Braarudosphaera bigelowii blooms in Transylvania andthe Eastern Carpathians related to palaeoenvironmental
changes
Arapov et al. – High-diversity coccolithophorecommunities in the open central Adriatic Sea

INA18Argenio et al. – IODP Sites U1385 and U1313:
Coccolithophore calciﬁcation patterns from the Last
Glacial Maximum to the Holocene
Asanbe & Henderiks – The biogeographical extent
and global synchronicity of the Late Miocene
Reticulofenestra pseudoumbilicus paracme

9of coccolithophore calciﬁcation
Granchovski & Stoykova – Campanian–Maastrichtianboundary interval at Beloptichene (Kula tectonic unit, NW
Bulgaria): New nannofossil data

Bazzicalupo et al. – Coccolith assemblages inside
coralligenous build-ups: Some preliminary results from
Marzamemi (Sicily, Italy)

Granero Ordoñez & Wagreich – Aspidolithus
parcus/Broinsonia parca: Some aspects of nannofossil
morphometry around the Santonian–Campanian boundary
Habib et al. – Evolution and adaptation of coccolithophores
to recent environmental changes in the Mediterranean Sea

Bazzicalupo et al. – Coccolith assemblages and biomarker
response to climate variability in the last 20,000 years inthe southern Adriatic Sea

Hanson & Dunkley-Jones – Novel approaches to highresolution coccolith geochemistry through the Late
Pliocene Discoaster extinctions

Champigny & Rickaby – Effect of nutrient limitation on
the calciﬁcation of Gephyrocapsa oceanica and Chrysotila
roscoffensis

Hayat et al. – Coccolithophore export production in the
deep Ionian Sea, eastern Mediterranean (NESTOR site
sediment trap, 4300 m depth)

Chaumeil-Rodriguez et al. – Early to Middle Jurassic
calcareous nannofossil biostratigraphy: A preliminary
scheme for southwestern Gondwana

Holcová & Scheiner – An experimental study on postmortem dissolution and overgrowth processes affecting
coccolith assemblages: A rapid and complex processĆorić & Kallanxhi – Calcareous nannofossils from theMiddle/Upper Miocene succession of Pécs-Danitzpuszta(Lake Pannon), southern Hungary

Jiang et al. – Upper Cretaceous calcareous nannofossils
from Gamba, southern Tibet, and their palaeoceanographic
implications

Dauvier et al. – The effects of pelagic carbonate
production on the Pleistocene carbon cycle

Karatsolis et al. – Middle Miocene to Pleistocene
nannofossil biostratigraphy of the North Atlantic:
Preliminary results from IODP Expedition 395C,
Reykjanes Ridge

Fioroni et al. – Nannofossil response to the Late
Oligocene warming event at ODP Site 929 (Ceara Rise,
western equatorial Atlantic Ocean)Godbillot et al. – Response of marine nannoplankton toenvironmental forcings: Insights from automated imaging
methods on community shifts in the Gulf of Lions overthe last decade
González Martín et al. – Reconstruction of surface-ocean
dynamics during Termination V (MIS 12–MIS 11) on the
Iberian margin (IODP Site U1386)
González-Lanchas & Rickaby – Coccolith carbon vitaleffects in understanding the photosynthetic underpinnings

Liu et al. – Evolution of Miocene calcareous nannofossil
assemblages and palaeoceanographic research in theSouth China Sea
Marconato et al. – Calcareous nannofossils across theCampanian–Maastrichtian in the high-productivity system
of Aderet, Shefela Basin, Israel
Martín García et al. – Messinian–Pliocene
chronostratigraphy and palaeoceanography of IODP Site
1387: The calcareous nannofossil washing–winnowing
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Ma Xiaoxu et al. – Coccolithophore physiology and themolecular mechanism response to the seawater Mg/Ca
ratio
Minoletti et al. – Separation of coccoliths from sediments:
An automated protocol for palaeoclimatic investigations
Mossell et al. – Surface-water variations during the
Middle and Late Pleistocene in the Mozambique Channel
based on calcareous nannofossil assemblagesPedrão et al. – Coccolithophore palaeoproductivity in the
SW Atlantic during the last seven terminations
Pérez Panera – Late Triassic calcareous nannofossils
from Argentina and Peru unravel an early dispersal
pathway through Panthalassa
Persico et al. – Paleogene calcareous nannofossils fromIODP Site U1553: Biostratigraphic, palaeoecological andpalaeoceanographic implications
Razmjooei et al. – Mid-Pleistocene to Holocene
calcareous nannofossil taxonomy and biochronology of
the central Arctic Ocean
Rigual-Hernández et al. – Role of coccolithophore
ﬂoristics on alkenone-derived temperatures in thesubantarctic Southern Ocean
Sarkozi & Rickaby – The effect of temperature on
the photosynthetic underpinnings of coccolithophore
calciﬁcation
Schneider et al. – Late Holocene ecological trends in theLevant Basin from fossil phytoplankton assemblages
Shah et al. – Calcareous nannofossil assemblages in
sediment cores of the northern Red Sea: First results andpalaeoecological reconstructions
Simonato et al. – Correlation of the calcareous nannofossil
biostratigraphy between the Cenomanian–Turonian
Poigny core and Quero section

Skejić et al. – Coccolithophore assemblages from thecentral Adriatic Sea
Stoykova et al. – Did the 33.4-Ma eastern Rhodope
supereruptions contribute to Early Oligocene cooling?
Calcareous nannofossil data from the St. Sozon section,
Limnos Island, Greece
Stoykova et al. – PETM Riben section revisited (northern
Bulgaria, SE Europe): New nannofossil and foraminiferal
isotope data
Svobodová et al. – Jurassic–Cretaceous boundaryinterval in the Ropice section from the perspective ofbiostratigraphy, stable isotopes and palaeomagnetism
Trotta et al. – Coccolithophore responses topalaeoenvironmental variability in the Gulf of Cadiz(IODP Site U1387) through MIS 48–MIS 45
Vollmar et al. – Surface-sediment coccolith assemblages
and Emiliania huxleyi morphotype calciﬁcation across the
Drake Passage, Southern Ocean
Wang Xuejiao et al. – Interregional correlations and sealevel changes in the Middle Paleocene–Early Eocene of theeastern Tethys Sea (Central Asia): Calcareous nannofossil
evidence from the western Tarim Basin, NW China
Zhou & Liu – Evolution of upper seawater stratiﬁcation in
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Coccolithophore distribution in a north-western
Mediterranean delta system
Marina Addante
Department of Earth and Environmental Sciences, University of Bari Aldo Moro, Bari, Italy & Institut de Ciència i Tecnologia Ambientals,
Universitat Autònoma de Barcelona, Bellaterra, Spain; marina.addante@uniba.it

Michaël Grelaud
Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Bellaterra, Spain

Patrizia Maiorano
Department of Earth and Environmental Sciences, University of Bari Aldo Moro, Bari, Italy

Marta Alvarez
Instituto Español de Oceanografía, Paseo Alcalde Fco Vazquez Nº10, A Coruña, Spain

Sergio Bonomo
Institute of Environmental Geology and Geoengineering, National Research Council (IGAG-CNR), Monterotondo (RM), Italy

Patrizia Ziveri
Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Bellaterra, Spain

Coccolithophores are considered to be dominant in pelagic and oligotrophic systems. For this reason, there is a lackof studies in coastal areas. We present the living coccolithophore distribution and diversity in the Catalan coastal areafrom Barcelona to the Ebro Delta (Spain), as revealed by the analysis of 77 water samples from 11 hydrographic stations sampled during the MERS research cruise (24–28 November, 2019). The sampled transects span the coastal andoffshore systems from 5–200 m water depth. The coccolithophore distribution was integrated with the seawater environmental parameters (nutrients, carbonate chemistry, light penetration, salinity, etc.) collected during the cruise. The mostabundant coccolithophore species at all the stations was Emiliania huxleyi, likely related to the sampling season (end ofsummer stratiﬁcation and increase in nutrient availability), followed by subordinate species, such as Gephyrocapsa spp.,
Syracosphaera spp., Algirosphaera robusta, Helicosphaera carteri, Rhabdosphaera spp., Coronosphaera mediterranea, Calciosolenia spp. and Florisphaera profunda. At the 11 sampled stations, the highest cell concentrations generally
occurred within the top 50 m of the water column. The maximum coccolithophore standing stocks were recorded between 5 and 50 m. The highest standing stocks occurred in the nearshore stations (5.1 × 104 coccospheres/L), associatedwith vertical mixing and the nutrient supply from river input. No clear vertical species zonation was observed in theseshallow-water stations, nor a signiﬁcant variation in the environmental parameters with depth, suggesting a rather homogeneous and mixed water-column. Moving from more coastal to offshore stations, a slight decrease in CD occurred.
In the offshore stations, the standing stock peaks were deeper and had lower values, and despite the dominance of E.
huxleyi, a vertical zonation in the community was observed. An upper-photic-zone (UPZ) group (Rhabdosphaera spp.,
Syracosphaera pulchra, C. mediterranea, Syracosphaera anthos, Umbellosphaera tenuis and Discosphaera tubifera),
although rare, occurred in the top 50 m, while the deep-dwellers––F. profunda and Gladiolithus ﬂabellatus––occupied
the lower photic zone (LPZ) from 75 m. The present study addresses the lack of knowledge of coccolithophore ecology
in coastal environments.

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Calcareous nannofossil assemblages and geochemical
analysis of Eocene oil shales from Wadi Ashajara, northern
Jordan, and their implications for the depositional
environment
Mohammad Alqudah
Department of Earth and Environmental Sciences, Faculty of Science, Yarmouk University, Shafeeq Irsheidat Street, 21163 Irbid, Jordan;
mohammad.alqudah@yu.edu.jo

Ali Momani
Department of Physics, Faculty of Science, Yarmouk University, Shafeeq Irsheidat Street, 21163 Irbid, Jordan

Mahmoud H. Altamimi, Jamal Nazzal, Mohammad S. Atawneh
Department of Earth and Environmental Sciences, Faculty of Science, Yarmouk University, Shafeeq Irsheidat Street, 21163 Irbid, Jordan

Eocene oil-shale deposits are particularly interesting among the organic-rich deposits in Jordan due to their depositionin the latest stage of the closure of the Neo-Tethys. Twenty-one oil-shale samples from the Wadi Ashajara section
were analysed for calcareous nannofossils and their biostratigraphy, palaeoecology, isotopic components and inorganic
geochemistry. These proxies offered some important insights into the depositional environment of the organic-richsedimentation during the Eocene. Based on the ﬁrst occurrences of the marker-species Discoaster sublodoensis,
Nannotetrina quadrata and Discoaster bifax, the Ashajara section was assigned to the Middle Eocene. Palaeoecologically,
many genera thrived during the Middle Eocene Climatic Optimum event. Signiﬁcant increases in the abundances ofReticulofenestra spp. and Coccolithus spp. during NP16 revealed a period of eutrophy dominating in the ocean in the
Middle Eocene. The clear shift in ecological strategy correlated with periods of increased nutrient supply (Fe, P, Al
and Si), suggesting that climate played a major role in increasing the abundance of the primary producers, therefore
enhancing the organic-rich environment in northern Jordan. Ecological shifts in the calcareous nannofossils were also
associated with shifts in oxygen, carbon, uranium and potassium isotopes. The presence of redox-sensitive elements(Fe, Ni and Cr) suggests that the oil shale in the study area was generally deposited in an anoxic environment. However,in some parts of the oil shale, elements with strong euxinic afﬁnities (Mo, Zn and V) exhibit the strongest enrichment,
which in turn indicates deposition of the oil shales in a euxinic to sub-euxinic environment.

INA1813

Calcareous nannofossils from the Samu Area (Campanian),
northern Jordan
Mohammad Alqudah, Haneen Ali Al-Sawaie, Waleed A. Al-saqqa
Department of Earth and Environmental Sciences, Faculty of Science, Yarmouk University, Shafeeq Irsheidat Street, 21163 Irbid, Jordan;
mohammad.alqudah@yu.edu.jo

Calcareous nannofossil assemblages were examined from the Campanian chalks of Wadi Samu in northern Jordan for
their biostratigraphy and palaeoecology. Samples were taken from a 30-m section composed mainly of chalk resting
unconformably on Santonian dolomitic limestones and underlain by chert–limestone sequences. The palaeoecologicalanalysis of the calcareous nannofossils in the studied samples depended on a set of statistical indices, including the total
number of nannofossils, their abundance, diversity, fertility and productivity. In addition, some species were selected todetermine temperature ﬂuctuations in the surface water that might indicate colder or warmer conditions. The calcareous
nannofossil assemblages in the Wadi Samu section had high diversity, with high abundances in particular genera, such as
Watznaueria spp. and Arkhangelskiella spp., which had good to moderate preservation. The logged section was divided
into two biozones (UC14 and UC15) based on the marker species. The palaeoenvironmental analysis emphasised thesigniﬁcance of cooling and fertility indicators, based on the preferences of nannofossil taxa in the reconstruction ofclimate and productivity models for the Tethyan Realm. Three intervals were characterised by cooler climates and thedominance of a eutrophic regime in the Campanian. The dominance of cooler-water species, such as Arkhangelskiellaconfusus, Eiffellithus turriseiffelii and Zeugrhabdotus erectus, in the three intervals associated with high-nutrient
species, such as A. confusus and Z. erectus, indicated the preference of these species for lower palaeotemperatures andhigh-nutrient regimes.

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Variations in primary productivity and assemblage
composition of coccolithophores in the Gulf of Papua overthe past 150 ka
Baizheng An
Linyi University, Linyi 276000, China; an.baizheng@gmail.com

Hanjie Sun
Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China

Luc Beaufort
Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France

Tiegang Li
Key Laboratory of Marine Sedimentology and Environmental Geology, First Institute of Oceanography, SOA, Qingdao 266061, China

The calcite plates that compose the exoskeletons of coccolithophores have a strong impact on the calcium carbonate
transport ﬂux from the sea surface to deep water. In this study, we used two Late Pleistocene sediment cores from theGulf of Papua (Western Paciﬁc; MD05-2049, MD05-2950). The changes in coccolith assemblage compositions andpalaeo-primary productivity over the past 150,000 years were reconstructed based on over 500 samples extracted fromthe sediment cores. The samples were prepared using the random settling method, and then 150 ﬁelds of view wereimaged for each sample using a SPOTFLEX camera. All the calcareous nannofossil were then identiﬁed and counted
automatically using the SYRACO system. The calcareous nannofossil assemblages were dominated by Florisphaera
profunda and members of the Noelaerhabdaceae (Gephyrocapsa and Emiliania).
We estimated the primary productivity conditions of the two cores based on the percentage of F. profunda. Preliminary
results show a correlation between primary productivity and precession in both cores. During MIS 5b–5a, the lowest
primary productivity (about 150 g C m-2 a-1) occurred at 82 ka BP, with strong seasonality indicated by high precession
values during this period. During MIS 5b–5a, the percentage of Gephyrocapsa ericsonii also decreased, from 60% to20%. Gephyrocapsa oceanica also varied following the primary productivity changes, with a higher percentage when
primary productivity was high, and a lower percentage when the primary productivity was low. However, Calcidiscus
leptoporus (contributing less than 1% to the coccolith assemblages) showed the opposite trend, with a higher percentage
when the primary productivity was lower. It is possible that different coccolithophores have different strategies forsurviving in variable environments. Gephyrocapsa oceanica easily dominates under high-productivity conditions,whereas C. leptoporus may have a better chance of survival under low-productivity conditions when other phytoplankton
are constrained by environmental factors.

INA1815

Oligocene Braarudosphaera bigelowii acmes in Transylvania
and the Eastern Carpathians related to palaeoenvironmental
changes
Eliza Anton, Mihaela Melinte-Dobrinescu
National Institute of Marine Geology and Geo-Ecology (GeoEcoMar), 23–25 Dimitrie Onciul St., 024053 Bucharest, Romania; antoneliza@
geoecomar.roBlooms of Braarudosphaera bigelowii are known to appear in several intervals, from Cretaceous times up to the
Holocene. It seems that this species is an opportunistic one that ﬂourishes when surface-water salinity is considerablychanged. Here, we focus on B. bigelowii occurrences in Romania in various Oligocene depositional settings. From the
Eocene–Oligocene boundary, when the Tethyan domain divided into the Mediterranean and the Paratethys, signiﬁcantpalaeogeographical changes took place in Central and Eastern Europe, implying a restricted circulation for the latter
realm and the occurrence of endemic faunas and ﬂoras. The salinity shifted across the whole Paratethyan region,
including in Transylvania and the Eastern Carpathians, where anoxic deposition occurred.
Analysis of the Lower Oligocene calcareous nannofossils from the aforementioned regions has highlighted theoccurrence of B. bigelowii acmes (representing around 60–70% of the total assemblages) in NP22 and NP23 (lowerpart). This interval contains, besides B. bigelowii, a small number of taxa (such as Reticulofenestra bisecta, R. umbilicus,
R. hillae, R. lockeri, Cyclicargolithus ﬂoridanus and Sphenolithus moriformis), all of them with low abundances.
Bulk sediment samples enriched in braarudosphaerids were characterised by increased values of δ18O. Up-section,
in NP23, the δ18O showed a decrease concomitant with lithological change (i.e. the deposition of laminated coccolithic
limestones). We speculate that the B. bigelowii acmes represent a single palaeogeographical/palaeoclimatic event, Early
Oligocene (Rupelian) in age, linked to regional (i.e. restricted circulation following isolation of the Paratethys domain)
and also global causes, related to the overall climatic deterioration during that time.

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High-diversity coccolithophore communities in the open
central Adriatic Sea
Jasna Arapov, Ana Bakrač, Sanda Skejić, Mia Bužančić, Živana
Ninčević GladanInstitute of Oceanography and Fisheries, Šetalište I. Meštrovića 63, 21000 Split, Croatia. arapov@izor.hr

A vertical proﬁle of a coccolithophore community was analysed using a scanning electron microscope (FESEM Tescan
MIRA3) in 2018. Sampling was conducted monthly at standard oceanographic depths (0, 10, 20, 30, 50, 75 and 100 m).
A total of 77 samples were analysed, with at least 100 cells being determined in each sample. The results showed highdiversity, with at least 133 morphotypes, out of which 84 species were in the heterococcolith and 42 in the holococcolith
phase.
The species Emiliania huxleyi was the most abundant and the most frequently occurring, while the Syracosphaera
genus was the most diverse, represented by 30 species. The contribution and diversity of holococcolithophore morphotypes
were signiﬁcantly higher in the upper photic zone to 30 m depth in the period from April to October. An extreme peakin HOL contribution was noticed in May in the deeper layers (at 75 and 100 m). Throughout the investigated period,
eight species were found as possible combination coccospheres––Algirosphaera robusta, Helicosphaera pavimentum,
Syracosphaera arethusae, S. bannockii, S. molischii, S. nodosa, S. pulchra and Pontosphaera japonica. Besides the
combination coccospheres of S. molischii and S. pulchra that were the most often recorded, the others were found only
as single specimens, and some in collapsed form. In general, combination coccospheres were mainly found at the surface
or at 10 m deep, with the greatest occurrence in April. The exceptions were six combination coccospheres of S. pulchra
COMB pirus in October at 50 m, and a single combination coccosphere of S. arethusae at 75 m.
Some recently described species were identiﬁed, including Calyptrosphaera lluisae Keuter, Young, Koplovitz,
Zingone & Frada, 2021, Calicasphaera bipora Keuter et al., 2021, Palusphaera crosiae Archontikis & Young, 2021 andpossibly Syracosphaera mediterranea HOL marisrubi type. In addition, the species Alisphaera pinigera, Gephyrocapsa
ericsonii ericsonii type, G. ericsonii protohuxleyi type, G. oceanica, Reticulofenestra sessilis, Syracosphaera
azureaplaneta, Pileolosphaera longistirpes, Oolithotus fragilis, Hayaster perplexus and Zygosphaera marsilii are newly
reported from the Adriatic Sea.

INA1817

Morpho-taxonomic reassessment of the extant
coccolithophores Ericiolus and Mercedesia
Odysseas A. Archontikis
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK; odysseas.archontikis@univ.ox.ac.uk

Josué G. Millán, Amos WinterDepartment of Earth and Environmental Systems, Indiana State University, Terre Haute, Indiana, USA

Jeremy R. Young
Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK

The genera Ericiolus Thomsen and Mercedesia Thomsen & Østergaard are distinctive extant coccolithophores that arecharacterised by monomorphic, monothecate coccospheres formed of small-sized, star-shaped nannoliths. Following
a review of SEM images from Mediterranean, Paciﬁc and Atlantic waters, 26 collapsed coccospheres with star-likenannoliths were identiﬁed. Observations on the morphologies and biometric assessments of these specimens revealed
the existence of two unreported morphotypes that differ morphologically from all currently known Ericiolus andMercedesia species. The results suggest that the two morphotypes possess nannoliths with, respectively: 1) threebifurcate rays, equally positioned and angled, and a central spine with a terminal knob; and 2) three coplanar rays withsmall bifurcations at their tips and delicate crystal laths extending up the rays. Based on this and a re-examination ofpreviously published species, we further discuss the taxonomic implications for the genera Ericiolus and Mercedesia.

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IODP Sites U1385 and U1313: Coccolithophore calcification
patterns from the Last Glacial Maximum to the Holocene
Carmen Argenio
Dipartimento di Scienze e Tecnologie, Università degli Studi del Sannio, Benevento, Italy; argenio@unisannio.it

José Abel Flores
Department of Geology, Universidad de Salamanca. Salamanca, Spain

Miguel Ángel Fuertes
Department of Didactics of Mathematics and Experimental Sciences, Universidad de Salamanca, Salamanca, Spain

Barbara Balestra
Environmental Science Department, American University, Washington, DC, USA & Paleobiology Department, National Museum of Natural History, Smithsonian, Washington, DC, USA & Institute of Marine Sciences, University of California–Santa Cruz, Santa Cruz, CA, USA

Filomena Ornella Amore
Dipartimento di Scienze e Tecnologie, Università degli Studi del Sannio, Benevento, Italy

The study of calcareous nannofossil assemblages from Integrated Ocean Drilling Program (IODP) Sites U1385 andU1313 has allowed us to document the climate transitions that occurred in the Atlantic Ocean since the Last Glacial
Maximum (LGM). The present study compared coccolith-based palaeoproductivity proxies, calciﬁcation and dissolution/preservation signals to provide a palaeoceanographic reconstruction of sea-surface dynamics.
The calciﬁcation of all analysed species showed a decrease from 25 ka towards the Holocene, testifying to a negative inﬂuence of higher CO2 values on nannoplankton calciﬁcation. This link was more evident at Site U1313, wheresize-normalised coccolith thicknesses were reduced during intervals of increased CO2, including the Heinrich Stadial 1(HS1), the Bølling–Allerød (B–A), the Younger Dryas (YD) and the Holocene. The parameter controlling calciﬁcation
during Heinrich events differed at the two latitudes––at Site U1385, it was mainly controlled by temperature, while at
Site U1313, it was hampered by poor light availability due to iceberg inﬂuence. Furthermore, the palaeo-assemblages
at Site U1313 were characterised, during HS1 and at the beginning of the LGM, by dissolution related to the effects of
the higher CO2 solubility in the colder ice-age ocean, as well as temperature. At Site U1313, contrary to Site U1385,
the constantly increasing CO2 concentration recorded during the B–A hampered both calciﬁcation and the degree ofpreservation.

INA1819

The biogeographical extent and global synchronicity of theLate Miocene Reticulofenestra pseudoumbilicus paracme
Joseph Asanbe, Jorijntje Henderiks
Department of Earth Sciences, Uppsala University, SE-752 36 Uppsala, Sweden; asanbejoseph@gmail.com

First documented in deep-sea sites in the tropical Indian Ocean and deﬁned as the “small Reticulofenestra interval”(Young, 1990) and the “Reticulofenestra pseudoumbilicus paracme” (Rio et al. 1990), the temporary disappearance ofR. pseudoumbilicus (>7 μm) during the Late Miocene lasted ~1.6 Myr (Backman & Rafﬁ, 1997). In this study, datasetsfrom 49 deep-sea drilling (DSDP, ODP and IODP) sites from all major ocean basins were reanalysed to evaluate theglobal extent and timing of the R. pseudoumbilicus paracme. Reported nannofossil bioevents were updated to the latest
geological time-scale to create a robust biostratigraphic framework for basin-to-basin as well as latitudinal comparisons.
This analysis conﬁrmed a prominent distribution of the paracme in the tropical and subtropical regions, where its timing
was largely synchronous. However, a later onset and shorter duration of the paracme at higher latitudes suggest that R.
pseudoumbilicus ‘left’ the tropics ﬁrst and remained in temperate regions for a much longer time. As already suggested
by Young (1990), these patterns are most likely the result of a combination of evolutionary controls and ecologicalinﬂuences.
Quantitative nannofossil analyses of ODP Site 806 (Ontong Java Plateau, western equatorial Paciﬁc) have provided
support for drastic ecological changes prior to the disappearance of R. pseudoumbilicus. Basin-wide increases in bulk
biogenic carbonate accumulation rates, denoting the start of the Late Miocene ‘biogenic bloom’, indicate large-scalechanges in pelagic export production in the tropics around the same time. We hypothesise that the R. pseudoumbilicus
paracme represents an ecology-inﬂuenced, regional extinction in the tropics or a migration to higher latitudes, where
it remained for another ~1.2–1.4 Myr before going extinct. Although it may have survived for a longer time at higher
latitudes, the reappearance of large Reticulofenestra morphospecies ~400–600 kyr later probably involved substantial
genetic change, in analogy to the repeated extinction and speciation cycles proposed for Pleistocene Gephyrocapsa
morphospecies (Matsuoka & Okada, 1990; Bendif et al., 2019).
References
Backman, J. & Rafﬁ, I. 1997. Calibration of Miocene nannofossil events to orbitally tuned cyclostratigraphies from Ceara Rise. In: N.J. Shackleton etal. (Eds). Proceedings of the Ocean Drilling Program, Scientiﬁc Results, 154: 83–99.
Bendif, E.M., Nevado, B., Wong, E.L.Y., Hagino, K., Probert, I., Young, J.R., Rickaby, R.E.M. & Filatov, D.A. 2019. Repeated species radiations in
the recent evolution of the key marine phytoplankton lineage Gephyrocapsa. Nature Communications, 10: 4234.
Matsuoka, H. & Okada, H. 1990. Time progressive morphometric changes of the genus Gephyrocapsa in the Quaternary sequence of the tropicalIndian Ocean, Site 709. In: R.A. Duncan et al. (Eds). Proceedings of the Ocean Drilling Program, Scientiﬁc Results, 115: 225–270.
Rio, D., Fornaciari, E. & Rafﬁ, I. 1990. Late Oligocene through Early Pleistocene calcareous nannofossils from western equatorial Indian Ocean (Leg115). In: R.A. Duncan et al. (Eds.). Proceedings of the Ocean Drilling Program, Scientiﬁc Results, 115: 175–235.
Young, J. 1990. Size variation of Neogene Reticulofenestra coccoliths from Indian Ocean DSDP cores. Journal of Micropaleontology, 9: 71–86.

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The heteromorphic haploid–diploid life-cycle ofcoccolithophores: Insights into the genetic fingerprint,
adaptive morphology, phylogeny, origin and maintenance ofa complex cycle
Marie-Pierre Aubry
Department of Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8066, USA; aubry@eps.rutgers.edy

The coccolithophores may be the most iconic example of an organism with a haplo-diplobiontic life-cycle, with adimorphism so extreme that their exoskeletons were commonly assigned to separate species and genera when ﬁrst
described. A wealth of data has been recorded for the diploid phase of the coccolithophores, with comprehensive
syntheses of their biology, ecology and phylogeny. By contrast, knowledge of the more fragile haploid phase has lagged
to an extent that prevents a holistic approach to the study of coccolithophores in general.
This study was an attempt to remedy this chaotic situation. Based on a comprehensive description of the morphology
and structure of all described coccoliths and coccospheres secreted during the haploid phase, and a comparison between
those that are paired with a diploid counterpart and those that are not, an inclusive biological framework was establishedthat unites the haploid and diploid phases.
The implications of this effort are examined, including the leading role of morphostructural analysis in guiding theinterpretation of molecular phylogeny inferred from environmental databases, the modalities of adaptive morphology inoligotrophic waters, and the origination of a strongly differentiated haplo-diploid life-cycle in the earliest coccolithophores.
Importantly, the coccolithophores offer a unique opportunity to analyse the differences in phenotypic expressions of the
genome of a species during its haploid and diploid phases.
References
Aubry, M.-P. 2022. Coccolithophores: The calcifying haploid phase in living species. Biology, adaptive morphology, taxonomy. SEPM Concepts in
Sedimentology and Paleontology, 15: 402 pp.

INA1821

Occurrence and development of Emiliania huxleyi
morphotypes in the North Atlantic Ocean during the last
280,000 years
Karl-Heinz Baumann
University of Bremen, Department of Geosciences, Klagenfurter Strasse 2-4, D-28359 Bremen, Germany; baumann@uni-bremen.deAnne Strack
University of Bremen, MARUM – Center for Marine Environmental Sciences, Leobener Strasse 8, D-28359 Bremen, Germany

The currently accepted Emiliania huxleyi morphotype classiﬁcation is entirely based on modern samples, and thestratigraphic range of distinct morphotypes is unknown. Therefore, the main objective of this study was to investigate theoccurrence of known E. huxleyi morphotypes in the fossil record in the North Atlantic Ocean. Counts of morphometriccoccolith parameters were conducted using SEM, and measurements of these parameters on SEM images were analysedby discriminant analyses. The visual assignment of distinct coccoliths to known E. huxleyi morphotypes was validated
by group assignments using a leave-one-out cross-validation procedure.
Four known E. huxleyi morphotypes were distinguished––three lightly calciﬁed (Types A, B/C and O) and one
heavily calciﬁed (here named Type T), which corresponds to the known Type A overcalciﬁed morphotype. Furthermore,a new Reticulofenestra-like morphotype (Type R*) was observed, which is characterised by extensive distal-shieldcalciﬁcation. All investigated records showed a similar, but diachronous, size evolution of E. huxleyi coccoliths, withthe largest coccolith sizes occurring during MIS 4 and MIS 3. An increasing size trend with higher latitude, involving up
to 30% larger coccoliths, was also observed. In addition, low-latitude records showed a dominance of E. huxleyi TypeO, although this morphotype has previously been considered as a cold-water indicator. The results were validated in thecontext of information available from the cores.

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Coccolith assemblages inside coralligenous build-ups:
Preliminary results from Marzamemi (Sicily, Italy)
Pietro Bazzicalupo, Elisa Malinverno
Department of Earth and Environmental Sciences, University of Milano–Bicocca, Milano, Italy; pietro.bazzicalupo@unimib.it

Valentina Alice Bracchi
Department of Earth and Environmental Sciences, University of Milano–Bicocca, Milano, Italy & CoNISMa – National Inter-University
Consortium for Marine Sciences, Roma, Italy

Andrea Giulia Varzi
Department of Earth and Environmental Sciences, University of Milano–Bicocca, Milano, Italy

Alessandra Savini
Department of Earth and Environmental Sciences, University of Milano–Bicocca, Milano, Italy & CoNISMa – National Inter-University
Consortium for Marine Sciences, Roma, Italy

Luca Fallati
Department of Earth and Environmental Sciences, University of Milano–Bicocca, Milano, Italy

Adriano Guido
Department of Biology, Ecology and Earth Sciences, University of Calabria, Cosenza, Italy

Antonietta Rosso, Rossana Sanfilippo, Riccardo Leonardi
CoNISMa- National Inter-University Consortium for Marine Sciences, Roma, Italy & Department of Biological, Geological and Environmental
Sciences, University of Catania, Catania, Italy

Mauro Pietro Negri
Department of Earth and Environmental Sciences, University of Milano–Bicocca, Milano, Italy

Mara Cipriani
Department of Biology, Ecology and Earth Sciences, University of Calabria, Cosenza, Italy

Daniela Basso
Department of Earth and Environmental Sciences, University of Milano–Bicocca, Milano, Italy & CoNISMa – National Inter-University
Consortium for Marine Sciences, Roma, Italy

In the Mediterranean Sea, crustose coralline algae form endemic mesophotic reefs known as coralligenous build-ups.
These reefs are major hotspots for biodiversity and are characterised by a complex algal skeletal carbonate structurethat supports many organisms inside their numerous holes and crevices. In addition, the high porosity of these structures
leads them to act as sediment traps, potentially storing climatic and/or hydrological information.
Previous studies have investigated the composition of the sediments trapped inside coralligenous structures, although no studies have focused speciﬁcally on coccoliths. Because coccoliths are a well-known proxy for stratigraphic,climatic and hydrological changes, coccoliths trapped in coralligenous build-ups could potentially help us to understandthe growth of the bioconstruction.
Samples from two coralligenous build-ups were collected during the project FISR 04543 ‘CRESCIBLUREEF––
Grown in the blue: New technologies for knowledge and conservation of Mediterranean reefs’ (https://cresciblureef.
unimib.it/) from 36 and 37 m water depth off the coast of Marzamemi village (Sicily, Ionian Sea). Here, we present our
preliminary ﬁndings on the coccolith assemblages retrieved from inside these build-ups.
Abundant reworked coccolith taxa testify to river runoff/land erosion, reﬂected in the age of the taxa being in accordance with the stratigraphy on land. In addition, several extant taxa were identiﬁed. Given the relatively good preservation and the known stratigraphic distributions, we suggest that nannoplankton sedimentation from the upper watercolumn occurred during build-up development, highlighting the role of these bioconstructions as coccolith-snow traps.
These ﬁndings represent a preliminary assessment of the possibility of coupling coccolith analysis with coralligenous
build-up studies, helping to assess the hydrological/environmental changes affecting the coralligenous build-ups during
their lifespans. In this sense, comparisons between the coccolith assemblages and other biogenic components and theterrigenous sediments inside the coralligenous build-ups could be a powerful tool for unravelling local/regional hydrological and climatic changes.

INA1823

Coccolith assemblages and the biomarker response
to climate variability over the last 20,000 years in thesouthern Adriatic Sea
Pietro Bazzicalupo
Department of Earth & Environmental Sciences, University of Milano–Bicocca, Milano, Italy & Department of Earth & Geoenvironmental
Sciences, Università degli Studi di Bari Aldo Moro, Bari, Italy; pietro.bazzicalupo@unimib.it

Marie-Alexandrine Sicre, Vincent Klein
LOCEAN, Sorbonne Universités (UPMC, Univ. Paris 06)-CNRS-IRD-MNHN, Paris, France

Patrizia Maiorano
Department of Earth & Geoenvironmental Sciences, Università degli Studi di Bari Aldo Moro, Bari, Italy

The southern Adriatic Sea is a well-known area of high climatic sensitivity in the Mediterranean Sea, characterisedby a surface-water circulation deeply affected by wind stress and river runoff. These characteristics make it extremely
well suited to studying the last deglaciation and the Holocene, a period marked by vigorous long- and short-termclimatic ﬂuctuations (e.g. Siani et al., 2013; Jalali et al., 2018). In this work, we generated a high-resolution multi-proxyreconstruction (average of 80 yrs/sample), based on coccolithophore assemblages and marine and terrestrial biomarkers
from the deep-sea marine core ND14Q-AR2, retrieved from the South Adriatic Pit at 1013 m below sea level. The core
has a robust age-depth model, based on several tephra layers covering the last 20 kyr BP and 10 radiocarbon dates(Totaro et al., 2022).
The coccolithophore assemblages clearly show orbital-scale variations and short-term millennial- to centennial-scale
climate variability. These variations, interpreted as reﬂecting changes in the temperature, salinity and productivity ofthe surface waters, were used to shed more light on coccolithophore behaviour in the Adriatic Sea, which has thus far
been poorly explored. Marine biomarkers (alkenones) were used to reconstruct the sea-surface temperatures (SSTs)
and assess the organic-matter deposition on the seaﬂoor. Terrestrial biomarkers (n-alkanes, synthesised by terrestrial
higher plants) were measured to evaluate the terrigenous input into the Adriatic Basin, as well as the humidity changes
on land. These records clearly evidence the known climatic phases of the last 20,000 years, such as the Heinrich Stadial
1 (HS1), the Bølling–Allerød (B–A), the Younger Dryas (YD) and the Holocene. Several centennial- and millennialscale events (such as the Holocene Rapid Climate Changes [HRCCs]) superimposed on these main climatic trends werealso identiﬁed. The continental and marine proxies highlighted both a long-term temperature and humidity increase
and short-term wet–dry phases affecting the surface waters and marine productivity through freshwater discharge andterrigenous input. The overall analysis underlined the ability of calcareous nannofossils and biomarkers to capture highfrequency climatic ﬂuctuations in the Adriatic Sea.
References
Jalali, B., Sicre, M.-A., Klein, V., Schmidt, S., Maselli, V., Lirer, F., Bassetti, M.A., Toucanne, S., Jorry, S.J., Insinga, D.D., Petrosino, P. & Châles, F.
2018. Deltaic and coastal sediments as recorders of Mediterranean regional climate and human impact over the past three millennia. Paleoceanography and Paleoclimatology, 33: 579–593.
Siani, G., Magny, M., Paterne, M., Debret, M. & Fontugne, M. 2013. Paleohydrology reconstruction and Holocene climate variability in the south
Adriatic Sea. Climate of the Past, 9: 499–515.
Totaro, F., Insinga, D.D., Lirer, F., Margaritelli, G., i Caparrós, A.C., de la Fuente, M. & Petrosino, P. 2022. The Late Pleistocene to Holocene tephra
record of ND14Q site (southern Adriatic Sea): Traceability and preservation of Neapolitan explosive products in the marine realm. Journal ofVolcanology and Geothermal Research, 423: 107461.

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Evolution of Gephyrocapsa oceanica: Equatorial seasonality
at play
Luc Beaufort, Josué Dauvier
Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France; beaufort@cerege.fr

Today, there is virtually no seasonal change at the Equator because Earth orbits the sun in a nearly circular orbit. Thisorbit has periodically been more eccentric, producing a signiﬁcant annual asymmetry in the amount of sunlight received
at the Equator, which we call equatorial seasonality (ES). The evolution of the Noelaerhabdaceae has recently beenshown to have been driven by ES cycles (Beaufort et al., 2022). Another study has shown that the extant species of the
Noelaerhabdaceae evolved from a common ancestor that lived 500 ka by progressively diverging in size towards thepresent large spectrum of species-speciﬁc coccolith lengths (Bendif et al., 2019). This presentation will illustrate ourquantiﬁcation of the evolution of coccolith length in one of these species––Gephyrocapsa oceanica––over the last 500
kyr. We measured the sizes of more than 100 G. oceanica coccoliths in high-resolution samples collected from six cores
selected from the Indian and Paciﬁc Oceans and the Mediterranean Sea.
These records of G. oceanica coccolith size show similar trends––their size increased progressively from 500 ka to
100 ka, then decreased rapidly from 100 ka to the present value. This peak in size in the middle of the life of this species
indicates a non-monotonic evolutionary pattern. Because this peak is synchronous with a maximum eccentricity in thistime period, we conclude that this pattern supports the hypothesis of an inﬂuence of ES cycles on the size evolution of
Noelaerhabdaceae.
References
Beaufort, L., Bolton, A.C.T., Sarr, A.-C., Suchéras-Marx, B., Rosenthal, Y., Donnadieu, Y., Barbarin, N., Bova, S., Cornuault, P., Gally, Y., Gray, E.,
Mazur; J.-C. & Tetard, M. 2022. Cyclic evolution of phytoplankton forced by changes in tropical seasonality. Nature, 601: 79–84.
Bendif, E.M., Nevado, B., Wong, E.L., Hagino, K., Probert, I., Young, J.R., Rickaby, R.E.M. & Filatov, D.A. 2019. Repeated species radiations in the
recent evolution of the key marine phytoplankton lineage Gephyrocapsa. Nature Communications, 10: 1–9.

INA1825

How did calcareous nannoplankton respond topalaeoenvironmental-factor changes at low and highlatitudes in the Late Aptian–Early Albian interval?
Chiara Bettoni, Cinzia Bottini
Department of Earth Sciences, Università degli Studi di Milano, 20133 Milan, Italy; chiara.bettoni@unimi.it

Jens O. Herrle
Institute of Geosciences, Goethe University Frankfurt, Altenho ̈ferallee 1, D-60438 Frankfurt am Main, Germany

The geological record is characterised by case histories marked by profound changes in the ocean–atmosphere system,
such as the injection of a large amount of CO2, super-greenhouse conditions, oceanic anoxia, increased surface-water
fertility, and changes in bio-limiting metal concentrations. To better understanding such ecosystem variations, we study
calcareous nannoplankton, which are good palaeoecological tracers, being one of the most important calcifying groups
among the marine phytoplankton. Several studies on living coccolithophore species have demonstrated that they are very
sensitive to environmental changes (i.e. temperature, nutrient content, CO2 and trace metal concentration) that could affect their shapes, dimensions and abundances. However, it is still not clear which factors can alter nannofossil size inthe long-term, and if there is a different response in the average size of selected species dependent on palaeolatitude.
We studied a 14-Myr-long time interval from the Late Aptian to the Early Albian, which included a cooling eventand two oceanic anoxic events––OAE1a and OAE1b. We analysed the variations in abundance and size of selectednannofossil species with afﬁnities to temperature and fertility, such as Watznaueria barnesiae (oligotrophic species),
Rhagodiscus asper (warm water), Zeugrhabdotus erectus and Biscutum constans (mesotrophic species). Samples werecollected from two low-latitude cores––ODP Site 1049 (proto-North Atlantic Ocean) and the Piobbico core (Umbria–
Marche, western Tethys Basin, central Italian Apennines)––and from a high-latitude site––DSDP Site 511 (Falkland
Plateau, South America).
The morphometric results showed signiﬁcant dimensional and abundance variations, which followed similar patterns in the three studied sites, albeit with different mean sizes. For Site 511, the results showed that W. barnesiae andB. constans were larger than the specimens at low latitudes. Also, B. constans and Z. erectus displayed similar trends
in all studied sites, with a size reduction during OAE1a and a small average size from the end of OAE1a up to the endof OAE1b. In addition, the resistant and cosmopolitan species W. barnesiae, which commonly does not evidence coccolith size change, showed size variations that differed from those in B. constans and Z. erectus, possibly suggestingthat size was controlled by different palaeoenvironmental factors––whilst the W. barnesiae size seems to have depended
on temperature, the B. constans and Z. erectus sizes followed the surface-water fertility. The only exception was thesize drop across OAE1a, which affected all studied species, including R. asper, probably in response to surface-water
acidiﬁcation.

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Silicon in fossil and cultivated coccoliths of Helicosphaera
carteri: New insights from X-ray ﬂuorescence and infrared
spectroscopy analyses
Manuela Bordiga
National Institute of Oceanography & Applied Geophysics OGS, Via Auguste Piccard 54, 34151 Trieste, Italy

Alessandra Gianoncelli, Giovanni Birarda, Simone Pollastri, Valentina
Bonanni, Lisa Vaccari, Gianluca Gariani
ELETTRA – Sincrotrone Trieste, Strada Statale 14, km 163.5 in the Area Science Park, I-34012 Trieste–Basovizza, Italy

Diana Eva Bedolla
ELETTRA – Sincrotrone Trieste, Strada Statale 14, km 163.5 in the Area Science Park, I-34012 Trieste–Basovizza, Italy & AREA Science Park,
Padriciano 99, 34149 Trieste, Italy

Federica Cerino, Marina Cabrini, Alfred Beran
National Institute of Oceanography & Applied Geophysics OGS, Via Auguste Piccard 54, 34151 Trieste, Italy

Maurizio Zuccotti, Silvia Garagna, Giulia Fiorentino
Department of Biology & Biotechnologies “Lazzaro Spallanzani”, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy

Miriam Cobianchi, Claudia Lupi
Department of Earth & Environmental Sciences, University of Pavia, Via Ferrata 1, 27100 Pavia, Italy

Coccolithophores, one of the main marine calciﬁers, have signiﬁcantly impacted atmosphere–ocean CO2 exchanges andthe global carbon cycle through geological time by capturing CO2 through photosynthesis and permanently ﬁxing carbon
in their coccospheres, which are composed of micrometrical carbonate plates (i.e. coccoliths). However, the physiology
and proliferation strategies of coccolithophores are still poorly known, especially at the species-speciﬁc level. Recent
studies on DNA sequences have proved that some living species need silica transporters (SITs) or silica-like transporters (SILTs) to build coccoliths. To date SITs and SILTs have been identiﬁed in only a few species, such as Coccolithus
braarudii, Calcidiscus leptoporus, Prymnesium neolepis and Scyphosphaera apsteinii, whereas the species belonging
to the Isochrysidales, such as Emiliania huxleyi and Gephyrocapsa oceanica, do not record the presence of either SITs
or SILTs.
A deeper knowledge of silicon (Si)-requiring species is important for understanding their physiology and distribution, as well as the evolutionary steps driving the SIT and SILT strategy. To investigate the presence of Si in coccoliths,
we analysed, for the ﬁrst time, both cultured and fossil coccoliths in three beamlines of the Elettra Sincrotrone Trieste:
1) hard X-ray ﬂuorescence (XRF); 2) soft X-ray microscopy and low-energy X-ray ﬂuorescence (TwinMic); and 3) infrared spectroscopy (SISSI). We selected the species Helicosphaera carteri because: 1) it is heavily-calciﬁed; 2) its large
coccoliths made picking of the specimens easier; and 3) it belongs to the order Zygodiscales, which contains only one
species containing SILTs. Species-speciﬁc fossil coccoliths were picked, using a micromanipulator, from two deep-sea
sediment samples from the NW Paciﬁc (Ocean Drilling Program Site 1209) and deposited during Marine Isotope Stage(MIS) 5, which is considered to be a good analogue for modern warming, and during the previous glacial phase, MIS 6.
To dispel any bias derived from fossilisation processes, we also analysed single coccoliths extracted from monospeciﬁccultures of H. carteri grown under 290 ppm of CO2 to mimic the conditions recorded during MIS 5.
Thanks to these newly applied methodologies, we present preliminary results that show the presence of Si in boththe cultured and fossil H. carteri coccoliths. More speciﬁcally, the XRF beamline detected Si in the cultured sample atthe macro-scale, whereas the TwinMic microscope returned Si distribution maps for single coccoliths at the sub-micrometric scale. The SISSI beamline provided semi-quantitative data on the CaCO3 and Si content. Combining these multibeamline and multi-technique data, we documented higher Si contents in the cultured samples than in the fossil samples,INA1827

possibly due to preservational issues. Our data revealed the potentiality of the XRF, TwinMic and SISSI beamlines inanalysing the chemical composition of the inspected samples, both at the elemental and molecular scales, in both cultured and fossil coccoliths at the species level. This is pivotal in coccolithophore studies because monospeciﬁc elemental
analyses in the fossil record are extremely complex, if not almost impossible. This research was funded through MUR
for ECORD–IODP Italia.

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Calcareous nannoplankton as a useful tool in coastal
dynamics and (palaeo)environments
Mário Cachão
Faculty of Sciences & Instituto Dom Luiz, University of Lisbon, Campo Grande, 1749-016 Lisboa, Portugal; mcachao@fc.ul.pt

The sedimentological record of the calcareous nannoplankton is mainly studied in the oceanic domain where it occurs
with maximal abundances and diversity. However, for some time now, we have also been using its record as a tracerof the marine inﬂuence on coastal systems, such as rias, estuaries and coastal lagoons. Examples range from storm or
tsunamigenic deposits to sea-level-induced palaeoenvironmental changes.
Here, I present preliminary results from a new protocol for sampling sandy shores and quantifying their calcareous
nannoplankton and other coastal groups, such as ascidian (aragonite spicule taxa) and calcareous macroalgal (micronsized cell-wall fragments known as tubiliths) taphocoenoses. Still in the validation stage, this protocol uses a design ofthree replicates: 1) three beaches to characterise each coastal sector; 2) three samples to characterise each beach; and 3)
three scans to characterise each smear-slide.
Repeated three times throughout 2021 and 2022, this spatially high-resolution study covered three sectors––theopen-sea western Iberian Portuguese Atlantic coast (Santa Cruz, Rodízio and Guincho beaches), the outer Tagus Estuary(Cascais, Carcavelos and Algés beaches) and the inner Tagus Estuary (Alcochete, Montijo and Alfeite beaches). The
results corroborate the usefulness of calcareous nannoplankton for characterising between these distinct coastal domains.
Acknowledgements: This work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) IP/MCTES
through national funds (PIDDAC) – UIDB/50019/2020.

INA1829

Effect of nutrient limitation on the calcification ofGephyrocapsa oceanica and Chrysotila roscoffensis
Alfred Champigny
Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, UK & Université du Littoral Côte d’Opale, Boulogne sur Mer,
France; alfred.champigny@etu.univ-littoral.fr

Rosalind E.M. Rickaby
Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, UK

With global warming, it has been shown that the oceans will become more stratiﬁed, reducing the vertical supply ofnutrients from deeper nutrient-rich waters to the surface. Indeed, these exchanges are very important for all marine
plankton, especially in oligotrophic waters. Emiliania huxleyi has been described quite well in relation to these conditions,
whether it be the life-cycle, calciﬁcation or the polysaccharides that govern the calciﬁcation. We have examined different
species of coccolithophores (Gephyrocapsa oceanica and Chrysotila roscoffensis) under nutrient limitation to determine
whether there is a common response, particularly with regard to their ability to produce calcite, for the entire group orwhether responses differ among species. For E. huxleyi, it has been shown that calciﬁcation is enhanced, speciﬁcallywith an increase in the number of coccoliths produced and an increase in coccolith size, together with a decrease in
growth rate.
Experiments were carried out using semi-continuous batch cultures with reduced N and P availability in the laboratory.
Many parameters were studied, such as growth rate, cell size, and coccosphere and coccolith diameter, in order to better
understand whether signiﬁcant differences are present in the life-cycle of the cells. In addition, we calculated the calcite
production per day and per cell under each condition, which allowed us, for the ﬁrst time, to calculate production rates(ng cell-1 day-1) for these species under phosphate and nitrate limitation. Production values (mg day-1) in our cultures
allowed us to understand how the production rates of calcite may evolve at the community scale in response to nutrient
depletion. In particular, we explored whether there is a trade-off between growth rate and calciﬁcation rate, such thatslower-growing communities may still produce the same amount of calcite even when the calcite/cell may be increased.
We also explored how the morphometry of the coccoliths changed, which may help in identifying nutrient limitation infossil coccoliths in sediments. Finally, this research will help us to better understand how coccolithophorids and theircalciﬁcation acclimatise under nutrient limitation.

30

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Early to Middle Jurassic calcareous nannofossil
biostratigraphy: A preliminary scheme for south-western
Gondwana
Micaela Chaumeil-Rodríguez
CONICET – División Cientíﬁca de Geología, Museo de La Plata, Paseo del Bosque s/n, La Plata 1900, Argentina & Université Lyon, UCBL,
ENSL, UJM, CNRS, LGL-TPE, 69622, Villeurbanne 69100, France; micachaumeil@gmail.com

Emanuela Mattioli
Univ Lyon, UCBL, ENSL, UJM, CNRS, LGL-TPE, 69622, Villeurbanne 69100, France & Institut Universitaire de France, Paris, France; emanuela.
mattioli@univ-lyon1.fr

Juan Pablo Pérez Panera
CONICET – División Cientíﬁca de Geología, Museo de La Plata, Paseo del Bosque s/n, La Plata 1900, Argentina

Biostratigraphic studies on Early to Middle Jurassic calcareous nannofossils from the south-eastern Paciﬁc Ocean are
scarce and a local biostratigraphic scheme has not been developed yet. We present here the calcareous nannofossil
assemblages from the El Matuasto outcrop sections (I, II and III) in the Los Molles Formation, Neuquén Basin (Argentina),
dated as Lower Pliensbachian (NJT4) to Lower Bajocian (NJT9), according to the zonal markers of the Tethyan schemeby Ferreira et al. (2019). The assemblages showed a high diversity index and good preservation, allowing us to analyse
the evolution of the group, from the local to global scales.
The Pliensbachian succession was characterised by Calyculus sp., Crepidolithus granulatus, C. crassus,
Parhabdolithus liasicus, Similiscutum cruciulus group, S. ﬁnchii, S. giganteum, Tubirhabdus patulus and the ﬁrst
occurrences (FOs) of Crepidolithus pliensbachensis, Biscutum grande, Lotharingius barozii, Parhabdolithus robustus
and Lotharingius haufﬁi. The Toarcian was characterised by Axopodorhabdus atavus, Biscutum dubium, L. haufﬁi,
Orthogonoides hamiltoniae, S. cruciulus group, T. patulus and the FOs of Zeugrhabdotus erectus, Carinolithus
superbus, Watznaueria fossacincta, Discorhabdus striatus, D. criotus, Retecapsa incompta and Watznaueria contracta.
The Aalenian association was characterised by Biscutum intermedium, C. superbus, Calyculus sp., Discorhabdus sp.,
Ethmorhabdus sp., Lotharingius barozii, L. haufﬁi, L. sigillatus, Podorhabdus grassei, Similiscutum novum, Triscutumsullivanii, Watznaueria contracta, Zeugrhabdotus erectus and the FO of Watznaueria britannica. The Early Bajocian
contained the presence of B. intermedium, Discorhabdus sp., Ethmorhabdus sp., L. haufﬁi, L. sigillatus, P. grassei, R.
incompta, S. novum, W. britannica, W. contracta, W. fossacincta and Zeugrhabdotus erectus, with the last occurrence ofCalyculus sp.
The calcareous nannofossils reported in this contribution constitute the most time-expanded and continuous recordof the group in the Neuquén Basin and south-western Gondwana. The assemblage composition has many similarities
with western Tethys assemblages, but some discrepancies also occur, mainly in the FOs of some species. This deserves
to be further explored and a local biozonation scheme for the area should be established.

INA1831

Isolating and analysing the coccolith size fraction as a
metric for diagenesis
Shamar C. Chin
Department of Earth & Environmental Sciences, 115 Trowbridge Hall, University of Iowa, Iowa City, 52242 Iowa, USA; shamar-chin@uiowa.edu

David K. Watkins
Department of Earth and Atmospheric Sciences, University of Nebraska, Lincoln, 68588 Nebraska, USA

John A. Sarao
Department of Geology and Geophysics, 157 New Halbouty Hall, Texas A&M University, College Station, 77843 Texas, USA

Chelsea M. Bouslog, Samantha N. Eberly
Department of Earth & Environmental Sciences, 115 Trowbridge Hall, University of Iowa, Iowa City, 52242 Iowa, USA

Deriving palaeotemperatures using calcareous nannofossils presents challenges because of their size and diagenetic
overprint. An example is the cool-tropics paradox, which concluded that high-resolution imaging might not detect the
microscopic recrystallisation of calcite, posing a problem when analysing and interpreting the primary signal for palaeosea-surface temperatures. In order to develop more precise analyses for calcareous nannofossils as a palaeotemperature
proxy, it is necessary to continue exploring and reﬁning methods for isolating the coccolith-sized fraction. In addition,these methods will improve upon techniques used for picking individual coccoliths for high-lateral-resolution analyses.
In assessing primary temperature signals, studies have shown that, as the coccolith-sized fraction decreases in size,
temperatures also decrease. As a result, there is a need to recalibrate the metrics to determine the extent of diagenetic
alteration and the calculations for palaeotemperatures. Given these caveats, this study aimed to develop a cost-effective
method for assessing diagenesis in coccolith-rich sediments. Samples from the uppermost Albian–Lower Cenomanianof the North Atlantic Ocean (Deep Sea Drilling Project Leg 79, Site 547) were used for centrifugation. The samples wereprimarily nannofossil-bearing clays with moderately to well-preserved calcareous nannofossils. Using a surfactant, ultrasonication, centrifugation and decanting, the rotations per minute and speed were altered until a ﬁne-grained fraction,a coccolith-sized fraction and a coarse-grained fraction were produced. The integrity of the calcareous nannofossil assemblages was determined by comparing counts from the bulk sediment samples to those of the coccolith-sized fraction.
Using ImageJ, the mean areas of the grains were calculated for the ﬁne-grained fraction (0.073 µm2), the coccolith-sized
fraction (1.627 µm2) and the coarse-grained fraction (3.5366 µm2).
After separating the distinct size fractions from an interval with well-preserved calcareous nannofossils, the coccolith-sized fraction and bulk sediment samples were analysed for δ13C and δ18O to assess the effectiveness of the
proposed centrifugation method. The δ13C values of the coccolith-sized fraction and bulk sediment had similar trends
and a signiﬁcant positive correlation. However, the δ18O values for the coccolith-sized fraction and bulk sediments did
not have a signiﬁcant correlation. Furthermore, a signiﬁcant decoupling of the δ18O curves occurred at the Albian–Cenomanian boundary and terminated in the lowermost Cenomanian. The δ18O values for the bulk sediment samples
were characterised by a positive δ18O excursion throughout this interval, indicating lower temperatures when comparedto the coccolith-sized fraction. A plausible cause for the deviation in δ18O values could be diagenesis––a signiﬁcantamount of dolomite rhombs in the bulk sediment samples supports this hypothesis. By contrast, centrifugation removed
a signiﬁcant portion of the dolomite rhombs from the coccolith-sized fraction. Given these caveats, this method can beused to aid with estimating the extent of diagenesis. It is also important to note that the δ13C values were likely similar
due to low organic-matter concentrations throughout this section. Therefore, the amount of organic matter should befactored into any isotopic analysis. Based on these preliminary results, we conclude that isotopic analyses of the isolated
coccolith-sized fraction could be a potential metric for identifying diagenesis. Furthermore, this cost-effective method
does not require extensive sample preparation, and the parameters can be modiﬁed to account for different lithologies
and grain sizes.

32

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Eocene calcareous nannofossils from the Humor Basin(Eastern Carpathians, Romania): Biostratigraphy andpalaeoenvironmental reconstruction
Carmen Mariana Chira, Raluca Bindiu-HaitonicBabeş-Bolyai University, Department of Geology & Research Centre for Integrated Geological Studies, 1 Mihail Kogălniceanu Street,
400084 Cluj-Napoca, Romania; carmen.chira@ubbcluj.ro

The Rea Valley section in the Tarcău Nappe, which belongs to the Carpathian ﬂysch, was analysed in order to integrate
biostratigraphical, sedimentological and palaeoecological data. The studied section was located between Humor
Monastery and Poiana Micului village, and consisted of siliciclastic turbidites characteristic of deep-water deposition.
The calcareous nannofossils assemblages were quantitatively and qualitatively analysed. The studied samples werecollected from ﬁne-grained intercalations in the turbiditic sequence, at an interval of about 50 cm from each other.
For analysis of the calcareous nannofossil assemblages, the samples were processed using two different standard
micropalaeontological methods. Samples for the smaller foraminifera were processed following the classical method.
The abundances of calcareous nannofossils and foraminifera displayed variations through the section. Most samples
contained abundant microfossils, although a few were almost barren.
The calcareous nannofossil assemblages were generally rich in reticulofenestrids (reaching up to 80% in the basal partof the section), such as Reticulofenestra umbilicus (NP16––Lutetian to NP22––Rupelian), R. dictyoda, R. reticulata, R.
bisecta and R. minuta. Zygrhablithus bijugatus (NP9––Thanetian to NN1––Aquitanian), Discoaster lodoensis (NP12––
Ypresian to NP14––Lutetian), D. saipanensis (NP14––Ypresian to NP19–20––Priabonian) were also present in theanalysed samples (but not exceeding 5%). The assemblages also contained (in low percentages) Chiasmolithus gigas,
Pontosphaera pulchra, Pontosphaera sp., Coccolithus pelagicus, C. eopelagicus, Helicosphaera bramlettei (NP14––
Ypresian to NP25––Chattian), Helicosphaera carteri, Sphenolithus anarrhopus, S. moriformis, S. furcatolithoides(Lutetian–Bartonian), Lanternithus minutus, Neococcolithes sp., Braarudosphaera bigelowii, calcispheres and ascidian
spicules.
The foraminiferal assemblages were composed of coarsely agglutinated individuals with a moderate to good degreeof preservation. Typical deep-water agglutinated foraminifera, together with Ammolagena clavata, indicated bathyal
deposition. The calcareous nannofossil assemblages and smaller benthic foraminifera placed the deposits in the Middle
Eocene (NP17––Discoaster saipanensis Zone) of the Sucevița Formation. The palaeoecological information, based on
statistical interpretations (i.e. of diversity indices, abundances, clusters), suggested relatively favourable conditions in
the water-column.
The distribution of the calcareous nannofossil and foraminifera assemblages provided important criteria for facies
correlation and allowed a reconstruction of the regional evolution of the Humor Basin (northern Eastern Carpathians,
Romania).

INA1833

The mesostructural evolution of Nannoconus via ptychographic X-ray computed tomography
Rajkumar Chowdhury, Fabienne Giraud, Alejandro FernandezMartinez
Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000 Grenoble, France; rajkumar.chowdhury@univgrenoble-alpes.fr

Julio Cesar da Silva, Redhouane Boudjehem, Anico Kulow
Université Grenoble Alpes, CNRS, Grenoble INP*, Institut Néel, 38000 Grenoble, France

Baptiste Suchéras-Marx
Aix Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France

Gaston Garbarino
ESRF, 71 avenue des Martyrs, 38043 Grenoble, France

Jean Louis Hazemann
Université Grenoble Alpes, CNRS, Grenoble INP*, Institut Néel, 38000 Grenoble, France

Javier Perez
SWING Beamline, Synchrotron SOLEIL, L’Orme des Merisiers, BP48, Saint-Aubin, Gif-sur-Yvette, F-91192 France

Among the calcareous nannofossils present in the Early Cretaceous oceans, Nannoconus had the largest exoskeleton(5–30 µm) and was the main planktonic carbonate bio-producer. Knowledge of the organism that produced the 3D
conical exoskeleton of Nannoconus is nonexistent, but a detailed analysis of both the morphology and structure of theexoskeleton can give information about its mode of calciﬁcation and palaeobiology. The exoskeleton presents a great
variability of plate arrangements, which has allowed the recognition of nine morphogroups that appear successively
through the nearly 35 Myr studied and that could explain its success story. Furthermore, turnovers in abundance of thedominant morphogroups were observed, probably associated with environmental changes that may have caused theirmorphological evolution. The main question driving this study was, has the morphology evolved signiﬁcantly in adapting to the environment?
To better understand the exoskeleton construction and this variability, there was a need to correlate the Nannoconus
microstructure at the nanometer scale with the environment. To address this, we used ptychographic X-ray computed
tomography (PXCT), which determined the 3D structure of different Nannoconus specimens from various ages at thenanometre level (resolution of a few tens of nanometres). The need for high spatial resolution tomography was supported by the small size of the inner structural elements, on the order of ~100 nm thick and a few millimetres long.
Sediment samples containing well-preserved Nannoconus spp. were selected from Hole 603B of DSDP Leg 93 andthe Munk Marl Formation of the North Sea, ranging from Valanginian (~140 Ma) to Aptian (~113 Ma) in age. A ﬁltration process was applied to the sediment in suspension in order to increase the abundance of Nannoconus specimens.
Because Nannoconus recrystallises easily, the preservation state was veriﬁed using both optical and scanning electronic
microscopy. Raman microspectroscopy was used to characterise the mineralogy, revealing very pure calcite crystals.
Finally, more than 10 of the best-preserved Nannoconus specimens were isolated from the sedimentary matrix using
picking techniques developed by us. Once isolated, various species of Nannoconus were analysed using PXCT at the
SWING experimental station of the SOLEIL French synchrotron (June 2022), for evaluating the morphological evolution. Interpretation of the results obtained during this experiment is still in progress and will be presented at the meeting.

34

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Calcareous nannofossils from the Middle/Upper Miocene
succession of Pécs–Danitzpuszta (Lake Pannon), southern
Hungary
Stjepan Ćorić
Geological Survey of Austria, Neulinggasse 38, 1030 Vienna, Austria; Stjepan.Coric@geologie.ac.atMădălina-Elena Kallanxhi
Albanian Geological Survey, Rr. Myslym Keta, Tirana, Albania

Quantitative analyses of calcareous nannofossils were carried out on 109 Middle/Upper Miocene (Sarmatian/Pannonian,Upper Serravallian/Tortonian) samples from the 12–79-m interval of the Pécs–Danitzpuszta sand pit (Hungary). The
Danitzpuszta outcrop, located on the eastern outskirts of the city of Pécs, is the largest exposure of Pannonian whitemarls in Hungary. The sand pit itself exposes Upper Miocene Lake Pannon sediments.
All samples from the Pécs–Danitzpuszta outcrop contained low-diversity calcareous nannofossil assemblages. The
section can be divided into three intervals that reﬂect palaeoecological changes during the Late Sarmatian and Pannonian. Interval 1 is dominated by normal-marine nannofossils, such as Calcidiscus leptoporus, Reticulofenestra pseudoumbilicus, Sphenolithus moriformis and Syracosphaera spp., and by didemnid ascidian spicules (from sea squirts). This
assemblage points to warm, shallow oligotrophic marine conditions. A slight increase in eutrophication in the upper partwas probably caused by enhanced nutrient supply from rivers. Interval 2 displays very low diversity. The co-occurrenceof endemic Praenoelaerhabdus, and small and normal-marine Acanthoica cohenii and Syracosphaera spp. indicates adrop in salinity, which can be interpreted as a stepwise transition from marine to brackish lacustrine conditions. The
longest interval, Interval 3, is characterised by an alternation of monospeciﬁc assemblages with either ascidians (Perforocalcinella fusiformis) or Isolithus spp. Assemblages dominated by ascidians (P. fusiformis) are interpreted as periodsof shallowing based on the co-occurrence of diatoms and sponge remains in this interval. Contrastingly, the intervals
with abundant Isolithus spp. are interpreted as periods of slight deepening. In addition, a short interval with endemic
calcareous nannofossils (Bekelithella echinata, Noelaerhabdus spp.) also indicates a period of deepening in the basin.
Changes in the Pannonian assemblages were inﬂuenced by changes in the environmental circumstances, most probably
water depth and salinity.
Based on the abundance of R. pseudoumbilicus and the absence of S. heteromorphus and Cyclicargolithus ﬂoridanus,Intervals 1 and 2 can be attributed to the upper NN6 (and/or NN7) standard nannoplankton zone(s) (younger than 12.1Ma), and are interpreted here as belonging to the marine Late Sarmatian, whereas Interval 3 correlates with the brackishlacustrine Pannonian. Based on the occurrences of B. echinata and species belonging to the genus Noelaerhabdus, theupper part of the section was attributed to NN10. Our investigations show that the quantitative assessment of endemic
calcareous nannofossils might be a tool for stratigraphic correlation in the Pannonian. The applied statistical methods
document the response of nannofossil assemblages to the rapid environmental and palaeoecological changes that took
place during the Sarmatian and Pannonian (Upper Serravallian and Tortonian) in this part of the Pannonian Basin.

INA1835

The effects of pelagic carbonate production on the
Pleistocene carbon cycle
Josué Dauvier, Luc Beaufort, Laurence Vidal
Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France; beaufort@cerege.fr

The role of climate in biological evolution has often been documented, but the reverse is much more rare. In thisstudy, we tried to see if the evolution of coccolithophores could have inﬂuenced the marine carbon cycle (CaCO3
production and carbon isotopes). To do so, we studied a core collected off Tanzania, measuring stable carbon andoxygen isotopes in planktonic foraminifera and the ﬁne fraction (<30 µm), and coccolithophore-related parameters(assemblages determined by taxon in number, mass and morphology). A morphological diversity index (MDI), recently
used to quantify the evolution of the Noelaerhabdaceae, covaried signiﬁcantly with coccolith mass ﬂuxes and the stablecarbon isotopes. The MDI was very close to the recently published one. We show that the evolution of coccolithophores
can vary with the ﬁne fraction δ13C and the carbonate content in sediments, and thus is part of the oceanic carbon cycle.

36

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The Paleocene/Eocene boundary and emendation of the
NP9/NP10 zonal boundary of Martini (1971)
Eric de Kaenel
DPR, Chemin sous la Roche 4b, 1185 Mont-sur-Rolle, Switzerland; edekaenel@bluewin.ch

David Bord
Ellington Geological Services, 1414 Lumpkin Road, Houston, Texas 77043, USA

James J. Pospichal
BugWare Inc., 1615 Village Square Blvd, Ste. 8, Tallahassee, Florida 32309, USA

The reference section for the Paleocene/Eocene global boundary stratotype section and point (GSSP) is the Dababiya
Quarry near Luxor in Egypt. This section is considered to be the most complete Upper Paleocene to Lower Eocene
sequence representative of this boundary, with a 2.83 m Paleocene–Eocene Thermal Maximum (PETM) interval (coreand Recovery Phase I intervals, according to Röhl et al., 2007). A new analysis of this section, based on 56 samples,
was undertaken in 2022. The samples were collected at 2, 5 and 10 cm intervals by Khozyem et al. (2014). These were
processed for calcareous nannofossils and prepared on glass slides according to the settling technique described in De
Kaenel & Villa (1996). The preservation of the nannofossils was exceptionally good, except for in a 52-cm-thick dissolution interval (devoid of nannofossils) at the base of the PETM. The nannofossil simple diversity varied between 50
and 123 species below and above the barren interval. A total of 180 species were identiﬁed from the Upper Paleocene to
Lower Eocene. No reworking was observed.
According to the standard nannofossil zonation of Martini (1971), the NP9/NP10 boundary is placed at the lowest
occurrence (LO) of Tribrachiatus bramlettei and is usually used to approximate the Paleocene/Eocene boundary. Determining the exact position of the LO of T. bramlettei is problematic, however, because of the difﬁculties in distinguishingspecimens of the genus Tribrachiatus (a triradiate structure superimposed on another trigonal structure) from those of
the genus Rhomboaster (a cubic/rhombohedral form, albeit a ﬂattened or misshapen one) at the top of the PETM core/base Recovery Phase I intervals. Detailed observations of the structure and geometry of the inter-arm regions between
the spines were used here to distinguish between these two genera, but this also did not allow for a precise placement of
the NP9/NP10 boundary.
In the literature, the NP9/NP10 boundary has been placed within the PETM interval (e.g. Menini et al., 2022), at thebase of the genus Rhomboaster (e.g. Bybell & Self-Trail, 1997) or well above the PETM interval (Aubry et al., 2000).
These discrepancies are related to the position of the LO of T. bramlettei and the individual workers’ method for making(or not making) a distinction between it and Rhomboaster. In the Dababiya section, we observed the LO of the genus
Rhomboaster (the small cubic R. cuspis) at the base of the negative carbon isotope excursion (NCIE), and therefore at
the Paleocene/Eocene boundary, and the LO of the genus Tribrachiatus at the top of the NCIE. In order to clarify the
position of the NP9/NP10 boundary, the following changes to the standard nannofossil zonation of Martini (1971) areproposed:
NP9 – Discoaster multiradiatus Zone, emended
Deﬁnition: Interval from the LO (base) of Discoaster multiradiatus to the LO (base) of the genus Rhomboaster.
Authors: Bramlette & Sullivan (1961), emended de Kaenel, Bord & Pospichal.
NP10 – Tribrachiatus contortus Zone, emended
Deﬁnition: Interval from the LO (base) of the genus Rhomboaster to the LO (base) of Tribrachiatus contortus.
Authors: Hay (1964), emended de Kaenel, Bord & Pospichal.
These emendations will resolve the discrepancies around the position of the NP9/NP10 boundary and provide consistency for biostratigraphers working on the PETM interval. This boundary will be easier to recognise and would unify
the stage and biozone boundaries.

INA1837

References
Aubry, M.-P., Cramer, B.S., Miller, K.G., Wright, J.D., Kent, D.V. & Olsson, R.K. 2000. Late Paleocene Event chronology: Unconformities, notdiachrony. Bulletin de la Société Géologique de France, 171(3): 367–378.
Bramlette, M.N. & Sullivan, F.R. 1961. Coccolithophorids and related nannoplankton of the Early Tertiary in California. Micropaleontology, 1:
129–74.
Bybell, L.M. & Self-Trail, J.M. 1997. Late Paleocene and Early Eocene calcareous nannofossils from three boreholes in an onshore–offshore transectfrom New Jersey to the Atlantic continental rise. In: K.G. Miller & S.W. Snyder (Eds.). Proceedings of the ODP, Scientiﬁc Results, 150X: 91–110.
de Kaenel, E. & Villa, G. 1996. Oligocene–Miocene calcareous nannofossil biostratigraphy and paleoecology from the Iberia Abyssal Plain. In: R.B.
Whitmarsh, D.S. Sawyer, A. Klaus & D.G. Masson (Eds.). Proceedings of the ODP, Scientiﬁc Results, 149: 79–145.
Hay, W.W. 1964. Utilisation stratigraphique des Discoastérides pour la zonation du Paléocène et l’Eocène inférieur. Mémoires du Bureau Recherches
Géologiques et Minières, 28(2): 885–889.
Khozyem, H., Adatte, T., Keller, G., Tantawy, A.A. & Spangenberg, J.E. 2014. The Palaeocene–Eocene GSSP at Dababiya, Egypt––Revisited.
Episodes, 37(2): 78–86.
Martini, E. 1971. Standard Tertiary and Quaternary calcareous nannoplankton zonation. In: A. Farinacci (Ed.). Proceedings of the Second Planktonic
Conference, Roma 1970. Edizioni Tecnoscienza Rome, 2: 739–785.
Menini, A., Mattioli, E., Vinçon-Laugier, A. & Suan, G. 2022. Calcareous nannofossil biostratigraphy across the Paleocene–Eocene Thermal
Maximum. Newsletters on Stratigraphy, 55(1): 69–97.
Röhl, U., Westerhold, T., Bralower, T.J. & Zachos, J.C. 2007. On the duration of the Paleocene–Eocene Thermal Maximum (PETM). Geochemistry,
Geophysics, Geosystems, 8: Q12002.

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Early evolution of calcareous nannofossils in the Late
Triassic in the Neo- and Palaeo-Tethys Oceans
Isaline Demangel, Sylvain Richoz
Department of Geology, Lund University, Sweden; isaline.demangel@geol.lu.se

Silvia Gardin
Center for Research on Palaeobiodiversity & Palaeoenvironments, Sorbonne University, Place Jussieu, 4, 75252 Paris, France

Eugen Grădinaru
Department of Geology, Faculty of Geology & Geophysics, University of Bucharest, Romania

The evolutionary appearance of the calcareous nannofossils, and especially coccolithophorids, has been the focus ofseveral studies, with the oldest coccoliths having been reported from the Rhaetian. This project focused on the early
calcareous nannoplankton from the Late Triassic (Norian–Rhaetian, 227–201.3 Ma) with the aim of understanding theirimpact on ocean chemistry during this time. We investigated their emergence and evolution, in terms of their abundanceand spread across different latitudes and environments. The sediments analysed covered different palaeolatitudes,with sections from the western and southern Neo-Tethys Ocean, as well as from the Palaeo-Tethys Ocean, where no
calcareous nannofossils have previously been recorded. To tackle the problems of diagenesis and poor preservation thathave often impacted Upper Triassic sediments and the calcareous nannofossils in them, we used different methodologies
depending on the lithology. Both soft and hard calcareous lithologies were analysed directly using a scanning electron
microscope, with the soft lithologies also being investigated in standard smear-slides observed using a light microscope.
Our study reports on the ﬁrst coccoliths––not identiﬁed to the species level––from the Middle Norian (Alaunian 3,~215 Ma). The oldest coccolith species identiﬁed was Crucirhabdus minutus, observed in the Upper Norian (Sevatian),followed by Archaeozygodiscus koessenensis. The ﬁrst Crucirhabdus primulus was found in the Lower Rhaetian. Theseoccurrences suggest that C. minutus was the ancestor of the coccolithophorids and that there was a slow evolution overtime. Crucirhabdus primulus occurred ~4.2 Myr after the ancestral C. minutus, with the evolution of a new genus––
Archaeozygodiscus, represented by A. koessenensis––taking around 0.35 Myr. Detailed microscopic investigations havedetected two different inner structures in the conical Rhaetian forms belonging to Eoconusphaera. Based on this, a
new species––E. hallstattensis––has been described and E. zlambachensis was emended. In the western Tethys, these
two species represent new biostratigraphic markers for the Rhaetian, having short and well-deﬁned occurrences. The
Eoconusphaera species present some similar characteristics to other conical Mesozoic forms, such as Mitrolithus,
Calcivascularis and Conusphaera, all now classiﬁed as coccoliths. Throughout the Rhaetian, Prinsiosphaera triassica
was affected by biological and environmental stress conditions. First, with the occurrence of the Eoconusphaeraceae
introducing competition for resources, and second, palaeoenvironmental changes that altered its calciﬁcation potential,
leading to a size decrease from the Early Rhaetian. These two species––P. triassica and E. zlambachensis––have been
observed for the ﬁrst time in Romanian sections (northern Dobrogea), which were located in the Palaeo-Tethys Ocean
during the Late Triassic. They occur commonly, where present.
In the Upper Triassic, calcareous nannofossils have been observed in both hemispheres, but are restricted toshallow and proximal environments. The incertae sedis P. triassica dominates assemblages throughout the Upper
Triassic, whereas the coccolithophores increase slightly in abundance during the Lower and Middle Rhaetian, reachinga maximum abundance in the Upper Rhaetian. However, a comparison between the quantitative data and calcium
isotope measurements does not provide any evidence for a signiﬁcant inﬂuence of these calciﬁers on the geochemicalcomposition of the western Neo-Tethys Ocean.

INA1839

Morphometric changes in the genus Watznaueria in
the Toarcian–Aalenian: Implications for taxonomy,
biostratigraphy and evolution
Elisabetta Erba, Stefano Visentin, Giulia Faucher
Department of Earth Sciences, University of Milan, Milan, Italy; elisabetta.erba@unimi.it

We conducted a morphometric investigation of the genus Watznaueria in a Lower–Middle Jurassic pelagic section fromthe Lombardy Basin (western Tethys Ocean), where a continuous and complete succession crops out at Colle di Sogno,
with no evidence of siliciclastic or bioclastic input. In the evolutionary history of calcareous nannoplankton, the Toarcian–
Bajocian interval is particularly crucial because this was the time of the emergence and early diversiﬁcation of the genus
Watznaueria. Biomorphometric analyses were performed on the species W. colacicchii, W. contracta and W. britannica.
In the studied interval, along with specimens unequivocally attributable to these individual species, several specimens
appeared to be similar, but with some characters not corresponding to the diagnostic features as described in the formal
species deﬁnitions. Morphometric analyses were conducted on images taken using a Q imaging Micropublisher 5.0 RTV
digital camera mounted on a Leitz Laborlux optical polarising microscope, at 1250x magniﬁcation. The images wereanalysed using a PC with Q-capture Pro suite software adapted for nannofossil analysis. Measurements were taken using
ImageJ software, with an error of ±0.08 µm.
Regardless of the size of the coccolith and of the central area, the parameter that unequivocally allows the separationof W. colacicchii from W. contracta is the coccolith width (W)/central-area width (w) ratio. The W/w ratio remained
unchanged stratigraphically, allowing the unambiguous identiﬁcation of the ﬁrst occurrences of the two taxa. In theColle di Sogno section, several W. britannica specimens were smaller, thinner and more elliptical than the holotype. In
the literature, a wide range of coccolith lengths and widths, and a variety of morphologies of the bridge spanning thecentral-area, have been described. Our data showed a progressive increase in the coccolith size and a relative decrease in
ellipticity. We identiﬁed as W. britannica only those specimens fully consistent with the formal deﬁnition of the species,
while separating out a W. aff. W. britannica group comprising all specimens with different features. In addition, a new
species was determined based on a peculiar and diagnostic bridge spanning the central area.
The revised morphometry-based taxonomy allowed us to determine the Watznaueria biohorizons and revise the early
evolution of the genus. Through the Toarcian–Lower Bajocian interval, Watznaueria showed a progressive increase insize and in the W/w ratio, the latter due to shrinkage of the central-area. The structures in the central-area displayeda gradual change, from a cross to a two-button bridge to a single-button bridge, along with a tendency towards anincreasingly more closed central-area.

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Burning experiments on calcareous nannofossils:
Contribution to a better understanding of historic mortar
production
Janina Falkenberg, Joerg Mutterlose
Institute of Geology, Mineralogy & Geophysics, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany; janina.falkenberg@
rub.deLime-based mortars consist of lime, which is produced by burning naturally occurring limestones. The limestones areheated to ~900ºC. The burning causes the thermal decomposition of CaCO3 into CaO (i.e. quicklime) and CO2. Thevery reactive quicklime is slaked with water, producing Ca(OH)2 (i.e. lime). In a last step, lime reacts with CO2 in theatmosphere, forming solid CaCO3 again. Calcareous nanno- and microfossils are not expected to be present in lime
binders in mortars because of the high heating temperature. Unexpectedly, however, we have encountered the remainsof calcareous nannofossils in historic mortars and mortar-based materials.
To gain a better understanding of the behaviour of calcareous nannofossils during the burning procedure, four samples
were heated to nine temperature levels (100, 300, 500, 600, 700, 750, 800, 850 and 900ºC). Both, original and heatedsamples were analysed with respect to their nannofossil contents and preservation using settling slides. Our results
showed a decrease in absolute numbers and preservation from 500ºC upwards, but nannofossils were preserved up to
900ºC. Changes in the relative abundances of individual species showed that some taxa were more resistant to heat thanothers. This pattern is best explained by their different crystal sizes and forms, as well as their surface areas. Calcareous
nannofossil abundances, their preservation and the presence/absence of different nannofossil taxa can therefore be used
to estimate the burning temperature during quicklime production.
Our study provides a better understanding of historic mortar production, and also supplies information for thepreservation of monuments because new mortars can be made with the same material and under the same conditions as
those in the past.

INA1841

How do new phytoplankton species form in the open ocean?
Dmitry A. Filatov
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK; dmitry.ﬁlatov@plants.ox.ac.uk

El Mahdi Bendif, Odysseas A. Archontikis
Department of Earth Science, University of Oxford, South Parks Road, Oxford OX1 3AN, UK

Kyoko Hagino
Center for Advanced Marine Core Research, Kochi University, Monobe B-200, Nankoku, Japan

Rosalind E. M. Rickaby
Department of Earth Science, University of Oxford, South Parks Road, Oxford OX1 3AN, UK

Evolutionary genetic processes underpinning the speciation process in marine phytoplankton are not well understood.
Population size is a key parameter in evolutionary genetics, but evolution may work in rather different ways in relatively
small populations of terrestrial organisms and astronomically large populations of marine plankton. According topopulation genetics theory, natural selection works more efﬁciently in large populations. Thus, the adaptation process
is expected to be very efﬁcient in large populations, such as those found in the marine microplankton, and we may
expect the classic adaptation-driven Darwinian speciation scenario to play a major role in the evolution of new species
in the marine microplankton. However, our evolutionary genetic analysis of genome-wide DNA polymorphism datafor ﬁve species in the coccolithophore genus Gephyrocapsa (including Emiliania huxleyi) revealed the opposite trend––a predominance of speciation driven by extrinsic barriers to gene ﬂow rather than the gradual evolution of intrinsic
genetic species incompatibilities expected under the Darwinian speciation scenario. The best-ﬁtting scenario for all
speciation events analysed includes an extended period of complete genetic isolation followed by recent (last 14 kyr)secondary contact. This model supports the role of geographic or oceanographic barriers in population divergence andspeciation. The coincidence of species emergence with glacial inceptions suggests stronger isolation of the ocean basins
and increased segregation of low-latitude ecological niches during glaciations being important drivers of isolation andspeciation in the marine phytoplankton. The similarity across multiple speciation events implies the generality of thisinferred speciation scenario for marine phytoplankton.

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Nannofossil response to the Late Oligocene warming event
at ODP Site 929 (Ceara Rise, western equatorial Atlantic
Ocean)
Chiara Fioroni
Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, Via Campi, 103, 41125 Modena, Italy; chiara.
ﬁoroni@unimore.it

Isabella Raffi
Dipartimento di Ingegneria e Geologia, Università degli Studi “G. d’Annunzio” di Chieti-Pescara, Campus Universitario, via dei Vestini 31, 66013
Chieti Scalo, Italy

Davide Persico, Giuliana Villa
Dipartimento di Scienze chimiche della vita e della sostenibilità ambientale (SCVSA), Università degli Studi di Parma, Plesso di Scienze della Terra,
Parco Area delle Scienze 157A, 43100 Parma, Italy

The Late Oligocene Warming Event (Zachos et al., 2001; Zhang et al., 2013), occurring between ~26.5 and 24 Ma,
is still a poorly known climatic change, identiﬁed ﬁrst by deep-sea oxygen isotope data (Zachos et al., 2001; Pekar etal., 2006), and then recognised in the fossil record in a number of settings, both terrestrial (e.g. Wu et al., 2018) andmarine (e.g. van Simaeys et al., 2004; Villa & Persico, 2006; Alegret et al., 2008; Villa et al., 2014). It is characterisedby an inverse correlation between sea-surface temperature and pCO2, following cooling due to the Antarctic glaciation
during the Eocene–Oligocene transition. Proxy data indicate a period of warming and/or deglaciation during the Late
Oligocene, associated with declining pCO2 (Zhang et al., 2013; O’Brien et al., 2020). In this work, we investigated the
response of calcareous nannofossils to this climatic event at ODP Site 929 (Ceara Rise, equatorial Atlantic Ocean),through a high-resolution sample set. We ﬁrst developed a high-resolution biostratigraphic framework of the consideredtime interval, then quantitatively deﬁned the palaeoecological preferences of selected species, comparing their generaltrends with those deﬁned in other oceanographic settings, allowing the main assemblage variation to be correlated withthe multi-proxy surface-temperature record recently determined at ODP Site 929 for the Late Oligocene (O’Brien et al.,2020).
References
Alegret, L., Cruz, L.E., Fenero, R., Molina, E., Ortiz, S. & Thomas, E. 2008. Effects of the Oligocene climatic events on the foraminiferal record from
Fuente Caldera section (Spain, western Tethys). Palaeogeography, Palaeoclimatology, Palaeoecology, 269: 94–102.
O’Brien, C., Huber, M., Thomas, E., Pagani, M., Super, J.R., Elder, L.E. & Hull, P.M. 2020. The enigma of Oligocene climate and global surface
temperature evolution. Proceedings of the National Academy of Sciences, 117: 41.
Pekar, S.F., DeConto, R.M. & Harwood D.M. 2006. Resolving a Late Oligocene conundrum: Deep-sea warming and Antarctic glaciation.
Palaeogeography, Palaeoclimatology, Palaeoecology, 231: 29–40.
Van Simaeys, S., De Man, E., Vandenberghe, N., Brinkhuis, H. & Steurbaut, E. 2004. Stratigraphic and palaeoenvironmental analysis of the
Rupelian–Chattian transition in the type region: Evidence from dinoﬂagellate cysts, foraminifera and calcareous nannofossils. Palaeogeography,
Palaeoclimatology, Palaeoecology, 208: 31–58.
Villa, G., Fioroni, C., Persico, D., Roberts, A.R. & Florindo, F. 2014. Middle Eocene to Late Oligocene Antarctic glaciation/deglaciation and Southern
Ocean productivity. Paleoceanography, 29: 223–237.
Villa, G. & Persico, D. 2006. Late Oligocene climatic changes: Evidence from calcareous nannofossils at Kerguelen Plateau Site 748 (Southern
Ocean). Palaeogeography, Palaeoclimatology, Palaeoecology, 231: 110–119.
Wu, F., Miao, Y., Meng, Q., Fang, X. & Sun, J. 2018. Late Oligocene Tibetan Plateau warming and humidity: Evidence from a sporopollen record.
Geochemistry, Geophysics, Geosystems, 20: 434–441.
Zachos, J.C., Pagani, M., Sloan, L., Thomas, E. & Billups, K. 2001. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science,
292: 686–693.
Zhang, Y.G., Pagani, M., Liu, Z., Bohaty, S.M. & Deconto, R. 2001. A 40-million-year history of atmospheric CO2. Philosophical Transactions of theRoyal Society A, Mathematical, Physical and Engineering Sciences, 371: 20130096.

INA1843

Response of marine nannoplankton to environmental
forcings: Insights from automated imaging methods oncommunity shifts in the Gulf of Lions over the last decade
Camille Godbillot, Thibault de Garidel-Thoron, Luc Beaufort, Yves
Gally
Aix-Marseille Université, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France; godbillot@cerege.fr

Karine Leblanc, Cristele Chevalier, Thang D.Q. Le
Institut Méditerranéen d’Océanologie (UMR 7294 MIO), CNRS/Aix-Marseille Université/Université de Toulon/IRD, Marseille, France

Xavier Durrieu de Madron
Centre de Formation et de Recherche sur les Environnements Méditerranéens (UMR 5110 CEFREM), CNRS/Université de Perpignan – Perpignan,
FranceRecent evidence has shown a decrease in ﬁsh catches in the Gulf of Lions synchronous with a decrease in plankton size,
raising the question as to the processes involved. The ongoing RapMed project, which involves different laboratories
in Aix-Marseille Université, is aimed at providing a better understanding of the variability of planktonic communities
and their resilience to environmental changes in this sensitive region. At the base of the food web, diatoms andnannoplanktonic algae are critical in supporting the upper trophic levels. Here, we present the ﬁrst results of a study
initiated in May 2022, which aspired to identify shifts in the micro- and nannoplankton communities, and to review
the possible controls on the patterns observed. We apply automated microscope imaging to a decade-long record of
calcareous and siliceous nannoplankton shells provided by a sediment-trap series from the Gulf of Lions (MOOSELIONCEAU, 42ºN, 5ºE, ~2300 m deep). Using the machine-learning-based workﬂow of image classiﬁcation developed
as part of the RapMed project, we identiﬁed patterns in nannoplankton size and taxonomic community structure overthe last decade. The changes detected will be analysed in light of a long-term time-series of environmental variables
recorded at the same location.

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Isotopic response of Pleistocene coccoliths to an ambient
pCO2 change: A calibration experiment
Camille Godbillot
Institut des Sciences de la Terre de Paris (UMR 7193 ISTeP), CNRS, Sorbonne Université, Paris, France & Aix Marseille Université, CNRS, IRD,INRAE, CEREGE, Aix-en-Provence, France; godbillot@cerege.fr

Fabrice Minoletti
Institut des Sciences de la Terre de Paris (UMR 7193 ISTeP), CNRS, Sorbonne Université, Paris, France

Franck Bassinot
Laboratoire des Sciences du Climat et de l’Environnement (UMR 8212 LSCE), CNRS, CEA, Université Versailles Saint Quentin, Gif sur Yvette,
FranceMichaël Hermoso
Laboratoire d’Océanologie et de Géosciences (UMR 8187 LOG), CNRS, Université du Littoral Côte d’Opale, Université de Lille, IRD, Wimereux,
FranceFor geological periods where direct measurements of pCO2 performed on ice cores are not possible, the reconstruction ofthis key palaeoclimatic parameter can only be achieved through proxy data. Results from both in vivo cultures and cellmodelling biogeochemical studies have demonstrated a link between the biological fractionation of coccoliths and theCO2 concentration of the living environment of their producers––the coccolithophores. Changes in the CO2 levels of thesurface ocean also drive, on a geological timescale, the isotopic composition (vital effect) of Cenozoic coccoliths. These
results have encouraged the use of coccolith vital effects as proxies for seawater CO2 concentrations. However, a numberof potential biases may hinder the application of the empirical calibrations from culture experiments to wild coccolith
populations. This work formalises a transfer function linking the vital effects of fossil coccoliths to the constrained
values of Pleistocene CO2aq, with a view to developing a new tool for reconstructing older pCO2 levels.
The calibration relies on the carbon and oxygen isotopic analyses of puriﬁed fractions of coccoliths from the North
Atlantic core MD95-2037 across Termination II (~140–130 ka). Using the alkenone-based sea-surface temperature(SST) record available for the site, and atmospheric CO2 concentrations from Antarctic ice cores, we derived values
for the surface-ocean CO2 concentrations across the deglaciation. We quantiﬁed the changing magnitude of the vitaleffect of the coccoliths to the presumed forcing by CO2 and formulated a transfer function between the two parameters.
We found a control of CO2 concentrations on the isotopic difference (Δ18O, Δ13C) between coccoliths of different
sizes produced across the penultimate glacial–interglacial transition. We discuss the factors complicating the obtained
relationship, including the effect of growth-rate changes and/or air–sea disequilibrium. As a perspective of this work, we
discuss the possible application of this calibration to more ancient periods in the Cenozoic, where direct measurementsof pCO2 are not available.

INA1845

Experimental diagenesis and quantitative assessment of
Discoaster overgrowth
Blandine Godet, Nicolas Pige
Université Lyon 1, ENSL, UJM, CNRS, LGL-TPE, F-69622 Villeurbanne, France; blandinegodet@hotmail.fr

Emanuela Mattioli
Université Lyon 1, ENSL, UJM, CNRS, LGL-TPE, F-69622 Villeurbanne, France & Institut Universitaire de France (IUF)

The increase in pressure and temperature during burial diagenesis leads to the dissolution and overgrowth of carbonate
particles. Calcareous nannofossils represent a large part of the sediments deposited on the ocean ﬂoor, and their remains
undergo signiﬁcant changes during burial diagenesis that ﬁnally lead to a loss of the most delicate specimens. These
partially or totally dissolve, ultimately modifying the assemblage composition. Along with dissolution, overgrowthoccurs on the most resistant specimens, with subsequent changes in their morphologies.
This work aimed at quantifying the diagenesis-induced overgrowth in nannofossil assemblages, focusing on
Discoaster specimens, which have previously been described as calcite receptors during experimental burial diagenesis(Adelseck et al., 1973). The diagenesis protocol described in that paper is updated here, and well-preserved assemblages
from Paleogene and Eocene ODP samples (Leg 198, Site 1209) and a Pliocene sample from the Trubi Formationof Sicily were exposed to 27-day-long high-pressure (up to 1 kbar) and, separately, high-temperature (up to 300ºC)
conditions, using artiﬁcial seawater as the medium. Overgrown discoasters were then measured through morphometry
using a scanning electron microscope. This study allowed, for the ﬁrst time, a quantitative assessment of the degree ofovergrowth occurring in discoasters.
References
Adelseck, C.G., Geehan, G.W. & Roth, P.H. 1973. Experimental evidence for the selective dissolution and overgrowth of calcareous nannofossils
during diagenesis. Geological Society of America Bulletin, 84: 2755–2762. doi: 10.1130/0016-7606(1973)84<2755:eeftsd>2.0.co;2

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Calcification of the Gephyrocapsa complex during the MidBrunhes Event
Alba González-Lanchas
Previously Department of Geology, University of Salamanca, Spain now Department of Earth Sciences, University of Oxford, Oxford, UK; alba.
gonzalez-lanchas@earth.ox.ac.uk

José-Abel Flores
Department of Geology, University of Salamanca, Spain

Rosalind E. M. Rickaby
Department of Earth Sciences, University of Oxford, Oxford, UK

Andrés Rigual-Hernández
Department of Geology, University of Salamanca, SpainEl Mahdi Bendif, Odysseas A. Archontikis
Department of Earth Sciences, University of Oxford, Oxford, UK

Francisco J. Sierro, Montserrat Alonso-Garcia
Department of Geology, University of Salamanca, Spain

Coccolithophores of the Noelaerhabdaceae have contributed to modulating the global carbon cycle by increasing
carbonate export and burial rates due to their recurrent enhanced production in low-eccentricity scenarios with an ~400kyr cyclicity during the Pleistocene. Whether this variability also entailed a change in the degree of coccolithophore
calciﬁcation is unknown, but plausible, since regulation of the carbon cycle at this scale would necessarily involve deepchanges in the state of the ocean’s carbonate chemistry.
We analysed the morphometries (size and mass) of the dominant Gephyrocapsa complex during the last minimumeccentricity episode 400 kyr ago, encompassing the Mid-Brunhes Event (MBE), over a wide range of latitudinal
environments across the North Atlantic Ocean region and the Mediterranean Sea. We captured an enhancement inGephyrocapsa calciﬁcation coeval with high coccolithophore production led by mid-sized Gephyrocapsa specimens.
An analysis of the diversity of the Gephyrocapsa complex allowed us to determine an increased calciﬁcation expressedby an array of morphotypes at the different sites. Such widespread enhanced calciﬁcation across the Gephyrocapsa
complex supports the existence of a common trigger for a higher degree of calciﬁcation of a range of Gephyrocapsa
during the MBE. This feature is plausibly related to changes in the seawater chemistry, such as an increase in HCO3-,
that could explain the common response of Gephyrocapsa calciﬁcation observed at all sites.
This perspective critically underscores that the nature of the stimulus mediating orbital forcing and long-term
phytoplankton evolution or adaptation could be embellished by changes in seawater carbonate chemistry as a criticalcomponent.

INA1847

Reconstruction of surface-ocean dynamics during
Termination V (MIS 12–MIS 11) on the Iberian margin(IODP Site U1386)
María González Martin, José-Abel Flores, Alba González-Lanchas,Montserrat Alonso García, Francisco Javier Sierro
Department of Geology, University of Salamanca, Salamanca, Spain; mariaglezmartin@usal.es

María Fernanda Sánchez-Goñi
Université de Bordeaux, UMR CNRS 5805 EPOC, Pessac, France & Ecole Pratique des Hautes Etudes (EPHE), PSL University, Pessac, France

Gabriel Hes
Université de Bordeaux, UMR CNRS 5805 EPOC, Pessac, France & Département de Géosciences, École Normale Supérieure, PSL Université,
Paris, France

A high-resolution study of the glacial–interglacial transition MIS 12/MIS 11 (434–404 ka) was conducted by observing
the productivity patterns of coccolithophore assemblages from Site U1386 of the Integrated Ocean Drilling Program(IODP) with the aim of reconstructing the oceanic surface dynamics of the Gulf of Cádiz. In addition, the pollen record
from the same site provided information on the changes in wind and precipitation trajectories along the south-western
Iberian margin during Termination V (MIS 12/MIS 11). The study of MIS 11 is important as it is considered to be apotential Holocene analogue.
The coccolithophore primary productivity was reconstructed using a primary productivity proxy (PPP = N valuesof small Gephyrocapsa + N values of G. caribbeanica). Temperature changes were studied by analysing cold-surfacewater taxa of polar or subpolar origin (Coccolithus pelagicus) and warm-water taxa (WWT). To reconstruct the currents:
1) the percentage of reworked nannofossils from the Paleogene–Upper Cretaceous was analysed to understand thestrength of the Mediterranean outﬂow water (MOW); and 2) the productivity of G. muellerae (Atlantic-water taxon)and small Gephyrocapsa were measured to determine the inﬂuence of the Portugal Current (PC) in the region. The
pollen data provided insights into the climate of the continent and the strength of the westerlies in the period studied,and associated these with the variability of the North Atlantic Oscillation (NAO). The PPP and WWT group values werehigher in the interglacial, while C. pelagicus (cold-water taxon) was more abundant in the glacial. This indicates thatthe productivity limitation was due to temperature, ruling out that the changes were caused by nearby upwelling. The
reworked percentages conﬁrmed that the MOW was most intense during MIS 12, associated with a dry and cold climate,
and that it gradually decreased towards the interglacial. This may have triggered a resumption of Atlantic Meridional
Overturning Circulation (AMOC), leading to one of the warmest high-latitude interglacials of the last 800 kyr (MIS 11).
The PC was not very intense during MIS 12, but increased during the transition and stabilised at a medium intensity in
MIS 11.
Overall, the data from our study provide new evidence for the important role of glacial–interglacial temperaturechanges on the primary productivity of coccolithophores in the Gulf of Cadiz during Termination V, affected by oceanicand atmospheric circulation patterns.

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Aspidolithus parcus/Broinsonia parca: Some aspects ofnannofossil morphometry around the Santonian/Campanianboundary
Paula Granero Ordóñez, Michael Wagreich
Department of Geology, University of Vienna, Althanstraße Josef-Holaubek-Platz14 2, 1090 Vienna, Austria; paula.granero.ordonez@univie.ac.at

In nannofossil biostratigraphy, the bioevent that deﬁnes the base of the Campanian is the ﬁrst occurrence of large
Aspidolithus parcus parcus (Stradner, 1963) Noël 1969 or Broinsonia parca subsp. parca (Stradner, 1963) Bukry,
1969 (of Nannotax3). The morphometry of the Aspidolithus/Broinsonia group is essential to identify the subspeciesof the group. The generic attribution to Aspidolithus (without central-cross elements) or Broinsonia (with central-crosselements) is another problem in this taxon (see also Nannotax 3 and Miniati et al., 2020). So far, the evolutionarytransition during the Late Cretaceous goes from small morphotypes with wide central-areas (‘Broinsonia’ enormis[Shumenko, 1968] Manivit, 1971) to large morphotypes (>10 µm) with decreasing central-area widths and increasing
rim/shield widths (Aspidolithus parcus group).
We used, herein, two sections (Postalm/NCA, Loibichl/RFZ) from the Eastern Alps of Austria to document themorphometry around the Santonian/Campanian boundary interval using 100x magniﬁcation and an oil-immersion lightmicroscope for the morphometric measurements. The critical subspecies parameters were the maximum length (longdiameter) of the coccolith, the ratio of the width of the outer rim/shield (b) to the small diameter of the central-area (a)(e.g. Gardin et al., 2001). The number and arrangement of perforations in the central-area provided another characteristicfeature (e.g. Lauer, 1975). At Postalm (Wolfgring et al., 2018; moderate preservation with overgrowth), the bioevent wasmarked by the rare ﬁrst occurrence (FO) of large A. parcus parcus with long diameters of between 9.5 and 12.5 µm andthe b/a < 2. Five transitional morphotypes could be distinguished: 1) B. enormis subsp. 1, with a length of <9 µm (usually
6–8 µm) and a b/a ≥ 2; 2) B. enormis subsp. 2, with a length of <9 µm (usually 6–8 µm) and a b/a < 2 (usually down to1.3). Some authors have already included this subspecies into A. parcus parcus ‘small morphotype’ (e.g. Miniati et al.,2020; 3) A. parcus expansus (Wise & Watkins in Wise, 1983) Perch-Nielsen, 1984, with a length of >9 µm (usually >10µm) and a b/a ≥ 2 (usually 3–4); 4) A. parcus parcus, with a length of >9 µm (usually >10 µm) and a b/a < 2 to ≥1. Only
this form is considered to be the bioevent characterising the Santonian/Campanian boundary and the base for standard
zones UC14a (Burnett et al., 1998) and CC18a (Sissingh, 1977); and 5) A. parcus constrictus (Hattner et al., 1980)
Perch-Nielsen, 1984, with a length of >9 µm (usually 9.5–13 µm) and a b/a < 1, which deﬁnes the base of the standard
subzones UC14b and CC18b.
Adding data from the better-preserved Loibichl section, where the perforations in the central-area could easily beobserved due to very minor overgrowth, indicated the following: 1) B. enormis and the ‘small morphotypes’ of the A.
parcus group display rather different numbers of perforations between the two localities, with 12–20 (ROM) and 4–8(LOI). However, due to their small size, data bias was signiﬁcant. A. parcus expansus showed a variation of >20 to 8; 2)
the evolution of large A. parcus parcus saw a reduction in the number of perforations to around 5–8 (2 per central-area
sector); and 3) the FO of A. parcus constrictus was marked by a further reduction to about 4–6 (1–2 per central-area
sector), with an even smaller number in younger intervals.
References
Burnett, J.A., with contributions from Gallagher, L.T. & Hampton, M.J. 1998. Upper Cretaceous. In: P.R. Bown (Ed.). Calcareous nannofossil
biostratigraphy. British Micropalaeontological Society Publications Series, Chapman and Hall, London: 132–199.
Gardin, S., Del Panta, F., Monechi, S. & Pozzi, M. 2001. Chapter E4. A Tethyan reference record for the Campanian and Maastrichtian stages: The
Bottaccione section (central Italy)––Review of data and new calcareous nannofossil results. Developments in Palaeontology and Stratigraphy,
19: 745–757.

INA1849

Lauer, G. 1975. Evolutionary trends in the Arkhangelskiellaceae (calcareous nannoplankton) of the Upper Cretaceous of central Oman, SE Arabia.
Archives des Sciences de Genève, 28: 259–262.
Miniati, F., Petrizzo, M.R., Falzoni, F. & Erba, E. 2020. Calcareous plankton biostratigraphy of the Santonian–Campanian boundary interval in the
Bottaccione section (Umbria–Marche Basin, central Italy). Rivista Italiana di Paleontologia e Stratigraﬁa, 126: 783–801.
Sissingh, W. 1977. Biostratigraphy of Cretaceous calcareous nannoplankton. Geologie en Mijnbouw, 56: 37–56.
Wolfgring, E., Wagreich, M., Dinarès-Turell, J., Gier, S., Böhm, K., Sames, B., Spötl, C. & Popp, F. 2018. The Santonian–Campanian boundary
and the end of the Long Cretaceous Normal Polarity Chron: Isotope and plankton stratigraphy of a pelagic reference section in the NW Tethys(Austria). Newsletters on Stratigraphy, 51.
Young, J.R., Bown, P.R. & Lees, J.A. 2017. Nannotax3 website. International Nannoplankton Association. Accessed 2 May 2021. URL: https://www.
mikrotax.org/Nannotax3.

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Coccolithophore ballasting effect on marine microplastics
export and accumulation
Michaël Grelaud, Laura Simon-Sánchez, Patrizia Ziveri
Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Bellaterra, Spain; michael.grelaud@uab.cat

Since the early 1950s, annual global plastics production has increased exponentially, reaching 367 million t in 2020.
Through waste mismanagement, and illegal dumping, shipping or ﬁshery activities, for example, a large portion (~8–10
million t) ends up in the marine system every year (Boucher et al., 2017). Once in the environment, the plastic waste
undergoes fragmentation through various processes, leading to the formation of the notorious microplastics (1–5000µm) and nanoplastics (<1 µm). However, this ﬂoating contamination, which is concentrated in the ﬁve subtropical gyres(i.e. garbage patches), represents only 1% of the total budget (Koelmans et al., 2017), pointing to seaﬂoor sediments as
the ultimate destination for this pollution.
It was hypothesised that, in the ocean, the ﬂoating microplastics can form aggregates embedded in marine snow andfaecal pellets. The coupling of this biotic and abiotic removal is suspected to be the main pathway for microplastics
to reach the seaﬂoor, although the mechanisms behind this removal remain poorly understood. In order to test thishypothesis, we measured the accumulation of coccolithophores over the last ~60 yr in a well-preserved and dated
sediment core retrieved from the prodelta of the Ebro River (north-western Mediterranean Sea). These data werecompared to the accumulation of small microplastics (10–1000 µm) measured in the same core (Simon-Sánchez et al.,in review).
The results show that the microplastics mass accumulating in these sediments mimics the exponential increase inglobal plastics production over the last 70 yr, making comparison with the coccolithophore record irrelevant, unless the
exponential trend is removed from the microplastics record. In this case, the detrended microplastics record parallels
the absolute abundances of coccolithophores since the mid-1960s, showing, for the ﬁrst time, the direct relationshipbetween the surface export production and the removal of microplastics from the surface to the seaﬂoor.
References
Boucher, J. & Friot, D. 2017. Primary microplastics in the oceans: A global evaluation of sources. Gland, Switzerland: IUCN, 43 pp.
Koelmans, A.A., Kooi, M., Law, K.L. & van Sebille, E. 2017. All is not lost: Deriving a top-down mass budget of plastic at sea. Environmental
Research Letters, 12(11): 1–9.
Simon-Sánchez, L., Grelaud, M., Lorenz, C., Garcia-Orellana, J., Vianello, A., Liu, F., Vollersten, J. & Ziveri, P. In review. Sediment cores revealing
the plastic age? Microplastic preservation in coastal sedimentary records.

INA1851

Evolution and adaptation of coccolithophores to recent
environmental changes in the Mediterranean Sea
Majd Habib
CEREGE, Aix-Marseille Université, CNRS, BP80 Cedex4, 13545 Aix-en-Provence, France & National Council for Scientiﬁc Research in Lebanon,
National Center for Marine Sciences, Batroun, Lebanon; habib@cerege.fr

Abed El Rahman Hassoun
National Council for Scientiﬁc Research in Lebanon, National Center for Marine Sciences, Batroun, Lebanon

Luc Beaufort
CEREGE, Aix-Marseille Université, CNRS, BP80 Cedex4, 13545 Aix-en-Provence, France

The semi-enclosed Mediterranean Sea is a hotspot for climate change, where faster warming, deoxygenation andacidiﬁcation rates are a regular occurrence that have affected its unique marine ecosystems and, in particular, thecalcifying organisms, such as corals, foraminifera and coccolithophores. The latter are phytoplanktonic species that are
major carbonate producers in the modern oceans, and thus they play a major role in the oceanic carbon cycle.
The quantiﬁcation of coccolithophore assemblages and the assessment of their relationships with environmental
drivers is lacking in Lebanon. To address this, this work focused on studying the coccolithophore species in theupper 150 m of the eastern Mediterranean Sea off Batroun and Beirut. For comparison, samples from the western
Mediterranean Sea off Marseille were also studied. Seawater parameters (temperature, salinity, pH, alkalinity and total
dissolved inorganic carbon) were measured to derive the carbonate chemistry of the collected water. Our preliminary
results show that, while Emiliania huxleyi is the dominant species, several other species, such as Syracosphaera pulchra,
Rhabdosphaera clavigera and Florisphaera profunda were also found in abundance. Morphometric parameters, suchas area, mass and thickness of the coccoliths and coccospheres, were measured with the help of artiﬁcial intelligence
and automated morphometric software. Our results highlight the importance of several parameters in unraveling the
distribution of E. huxleyi. We found that the combined effects of several physical and chemical oceanic parameters
control the morphometry and abundance of coccolithophores in the Mediterranean Sea.

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Marine phytoplankton biogeography before the recent
global ocean warming
Kyoko Hagino, Yurika Ujiie, Masao Iwai
Center for Advanced Marine Core Research, Kochi University, Monobe B-200, Nankoku, Japan; hagino@kochi-u.ac.jp

Tatsuhiko Hoshino
Kochi Institute for Core Sample Research, JAMSTEC, Monobe B-200, Nankoku, Japan

Richard Jordan
Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata 990-8560, Japan

Masayuki Utsunomiya, Yuichiro Tanaka
Geological Survey of Japan, AIST, 1-1-1, Higashi, Tsukuba 305-8567, Japan

Jeremy R. Young
University College London, Gower Place, London WC1E 6BT, UK

El Mahdi Bendif
Department of Earth Science, University of Oxford, South Parks Road, Oxford OX1 3AN, UK

Ian Probert
Station Biologique de Roscoff, Place Georges Teissier, 29680 Roscoff, France

Global ocean warming has accelerated since the 1990s, resulting in the modiﬁcation of marine phytoplankton habitats.
However, the evidence of such an environmental impact on the marine phytoplankton is limited. During the 1960s
and 1970s, a huge collection of ﬁlter samples was obtained from across the world ocean by Profs Andrew McIntyre of
the Lamont–Doherty Earth Observatory and Hisatake Okada of Hokkaido University. Their ﬁlter collection provided
us with a unique opportunity to reconstruct the photic biosphere before the acceleration of ocean warming. Okada &McIntyre obtained over 5000 ﬁltered seawater samples, from which they revealed ﬂoral zones and seasonal changes in
the coccolithophores of the Atlantic and Paciﬁc Oceans based on electron microscope studies of ~1500 ﬁlter samples(e.g. McIntyre & Bé, 1967; Okada & Honjo, 1973; Okada & McIntyre, 1979). In this study, we assess the diversity of
coccolithophores and parmales through morphological and eDNA metabarcoding studies. Our comprehensive survey,
employing morphological–molecular approaches will provide important information on the phytoplankton community
structure in the 1960s–1970s, and will enable us to make a comparison with those found in the modern ocean. In thistalk, we will introduce our ongoing project, report on its current progress, and show some of our preliminary results
based on microscope observations and metabarcoding analyses.
References

Okada, H. & Honjo, S. 1973. The distribution of oceanic coccolithophorids in the Paciﬁc. Deep-Sea Research, 20: 355–374.
Okada, H. & McIntyre, A. 1979. Seasonal distribution of modern coccolithophores in the western North Atlantic Ocean. Marine
Biology, 54: 319–328.
McIntyre, A. & Bé, A.W.H. 1967. Modern coccolithophoridae of the Atlantic Ocean – I. Placoliths and Cyrtoliths. Deep-Sea Researchand Oceanographic Abstracts, 14: 565–597.

INA1853

Novel approaches to high-resolution coccolith geochemistry
through the Late Pliocene Discoaster extinctions
Emma M. Hanson, Tom Dunkley Jones
School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham, UK; Exh601@student.bham.ac.uk

The climatic transition from the warmer Pliocene to the high-amplitude glacial–interglacial cyclicity of the Pleistocene
was clearly associated with a series of species extinctions in the discoasters. Although these had previously been a major
component of tropical to subtropical calcareous nannofossil assemblages, they suffered throughout the Late Pliocene,
culminating in a series of ﬁve species extinctions over a period of ~1 Myr, with the ﬁnal occurrence of Discoasterbrouweri occurring at 1.9 Ma. The immediate proximal causes of the extinction are currently unknown, althoughthroughout this period, there was a clear trend in declining total coccolithophore species diversity and size, and an
overall transition into a more intensely glaciated climate state.
To investigate these events, a novel size separation technique was employed to generate high-resolution coccolithsized speciﬁc isotopic and Sr/Ca records throughout the Pliocene–Pleistocene transition from IODP Site U1482 (Exp.
363) on the north-western Australian continental margin. By utilising this novel technique, we were able to increase thespeed of sample processing to rapidly generate geochemical records from the large (~7–10 µm) versus small (<4 µm)
coccolith size fractions. In the isotope records, there was a consistent offset of ~1‰ in the carbon isotopes. These results
are consistent with previous low-resolution, but long-term, size-fraction isotopic records, and demonstrate that thesecarbon isotopic offsets are retained through orbital-scale variations in the climate system.

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Coccolithophore export production in the deep Ionian Sea,
eastern Mediterranean (NESTOR site sediment trap, 4300 m
deep)
Sikandar Hayat
National and Kapodistrian University of Athens, Faculty of Geology & Geoenvironment, Panepistimioupolis, 15784 Athens, Greece & Departmentof Earth Sciences, University of Lille 1, Cité Scientiﬁque, 59655 Villeneuve d’Ascq, France; sikandar.hayat.etu@univ-lille.fr

Elisavet Skampa
National and Kapodistrian University of Athens, Faculty of Geology & Geoenvironment, Panepistimioupolis, 15784 Athens, Greece

Alexandra Gogou, Spyros Stavrakakis, Constantine Parinos
Hellenic Centre for Marine Research, Institute of Oceanography, PO Box 712, 19013 Anavyssos, Greece

Maria Triantaphyllou
National and Kapodistrian University of Athens, Faculty of Geology &Geoenvironment, Panepistimioupolis, 15784 Athens, Greece

This study was the ﬁrst attempt to understand the coccolith ﬂux and its seasonal variability in one of the deepest parts of
the Mediterranean located in the south-eastern Ionian Sea. The study area has a complicated geomorphology, comprisingvalleys, steep slopes and deep basins (Stavrakakis et al., 2013). Sediments for microscopic analysis were obtained fromthe deepest time-series sediment trap (4300 m), moored at the NESTOR site from February 2015 to December 2017. The
quantitative analysis was carried out using 1000x magniﬁcation with a polarised light microscope. A total of 21 speciesof heterococcoliths were identiﬁed. The maximum coccolith ﬂux was observed for March 2015 (1.10 x 109 coccoliths
m-2 day-1) and the minimum value was recorded for June 2015 (1.25 x 108 coccoliths m-2 day-1). The dominant species inall the samples was Emiliania huxleyi, constituting 50–70% of the total coccolith count, while the second most abundantspecies was Florisphaera profunda, constituting 8–25% of the total coccolith count. Emiliania huxleyi and F. profunda,
together with Umbilicosphaera sibogae (up to 8%), Rhabdosphaera clavigera (up to 4.8%), Syracosphaera pulchra (upto 5.6%), Calciosolenia brasiliensis (up to 3.2%), Gladiolithus ﬂabellatus (up to 3.9%) and holococcoliths (up to 3%)
accounted for 95–97% of the total coccolith assemblages. The highest abundance of E. huxleyi was recorded in March
2015 (8.4 x 108 coccoliths m-2 day-1). The highest abundance of F. profunda was recorded in October 2015, contributing
1.40 x 108 coccoliths m-2 day-1 in the ﬁrst half of the month and 1.37 x 108 coccoliths m-2 day-1 during the second half.
The occurrence of complete coccospheres was rare, mostly due to the processing of the samples for coccolith analysis.
Only a few coccospheres of S. pulchra, E. huxleyi, U. sibogae, R. clavigera and Algirosphaera robusta were observed.
The average coccolith ﬂux for the NESTOR site at a relatively shallow depth (2000 m), as reported by Skampa et al.
(2020), was lower than that observed in the present study, and a time lag of 45 days was observed for the summer
maximum ﬂux between the two traps. This time lag between the shallow and deep-water coccolithophore maxima has
also been reported from other studies in the eastern Mediterranean, such as the Cretan Sea (Triantaphyllou et al., 2004).
The higher coccolith ﬂux at 4300 m compared to the shallower depth can be attributed to lateral advection, resuspension
and/or the inﬂuence of eastern Mediterranean deep waters (EMDWs) (Stavrakakis et al., 2013). The summer maxima
observed by Skampa et al. (2020) at 2000 m appeared in early autumn at 4300 m (present study). A plausible explanation
for this unusual summer peak could be linked to physical processes that enhance the availability of nutrients in thesurface waters, such as upwelling processes due to seasonal anticyclonic-gyre variability and atmospheric input.
Acknowledgement: Erasmus Mundus Joint Master’s Degree Program PANGEA.
References
Skampa, E., Triantaphyllou, M.V., Dimiza, M.D., Gogou, A., Malinverno, E., Stavrakakis, S., Parinos, C., Panagiotopoulos, I.P., Tselenti, D.,
Archontikis, O. & Baumann, K.H. 2020. Coccolithophore export in three deep-sea sites of the Aegean and Ionian Seas (eastern Mediterranean):
Biogeographical patterns and biogenic carbonate ﬂuxes. Deep Sea Research Part II: Topical Studies in Oceanography, 171: 104690.

INA1855

Stavrakakis, S., Gogou, A., Krasakopoulou, E., Karageorgis, A.P., Kontoyiannis, H., Rousakis, G., Velaoras, D., Perivoliotis, L., Kambouri, G.,
Stavrakaki, I. & Lykousis, V. 2013. Downward ﬂuxes of sinking particulate matter in the deep Ionian Sea (NESTOR site), eastern Mediterranean:
Seasonal and interannual variability. Biogeosciences, 10: 7235–7254.
Triantaphyllou, M.V., Ziveri, P. & Tselepides, A. 2004. Coccolithophore export production and response to seasonal surface-water variability in theoligotrophic Cretan Sea (NE Mediterranean). Micropaleontology, 50: 127–144.

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Rates of phenotypic evolution in coccolithophores
Jorijntje Henderiks
Department of Earth Sciences, Uppsala University, SE-752 36 Uppsala, Sweden; jorijntje.henderiks@geo.uu.se

Kjetil L. Voje
Natural History Museum, University of Oslo, NO-0562 Oslo, Norway

By studying coccolithophores and their fossil coccoliths, we may gain detailed knowledge about the actual workings ofphenotypic evolution. However, despite many efforts to describe the tempo and modes of evolution from the fossil record,
it remains difﬁcult to identify the processes responsible for the patterns observed. Fossil coccolith time-series offer someof the most detailed and well-sampled records of evolutionary change, spanning millions of years, which can also bereadily compared to proxy records of past climates to address a range of process-oriented questions. Much work has been
done to document the patterns of past diversiﬁcation and phenotypic change in coccolithophores, and several working
hypotheses have been formulated that address distinct macroevolutionary coccolith size changes in terms of speciationand climatic adaptation. Yet, concerted efforts to understand what actual processes and rates of evolution underpin
the observed patterns have only just begun and, to date, studies have mainly focused on one single coccolithophorefamily––that of the ubiquitous species, Emiliania huxleyi, and its closest relatives in the Noelaerhabdaceae family. Here,
we present an analysis of the rates of phenotypic evolution in several coccolithophore lineages, and explore why thesevary across time-scales. We use a range of statistical models to describe and discuss ‘bursts of evolution’, as well as themore stationary trait dynamics during ‘evolutionary stasis’.

INA1857

An experimental study on post-mortem dissolution andovergrowth processes affecting coccolith assemblages: A
rapid and complex process
Katarína Holcová
Institute of Geology and Palaeontology, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic; holcova@natur.cuni.cz

Filip Scheiner
Institute of Geology and Palaeontology, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic & Institute of Geology of the Czech
Academy of Sciences, Rozvojová 269, 165 00 Praha 6 Lysolaje, Czech RepublicThis study summarised the effects of short-lasting pH oscillations on post-mortem coccolith morphological features
and the abundances and compositions of calcareous nannoplankton assemblages in three distinct types of material: 1)
Cretaceous chalk; 2) Miocene marls; and 3) Late Holocene calcareous ooze. Two independent experimental runs in asemi-enclosed system setting were realised in order to observe changes in the assemblages. One experiment was realisedwith no barrier to the survival of bacteria and, by contrast, the second inhibited their potential effect on the studied
system. The pH was gradually decreased in the range of 8.3–6.4 using a simpliﬁed reaction of CO2 with H2O to form aweak carbonic acid (H2CO3), thereby affecting CO32- and Ca2+ mobilisation. In addition, a subsequent overgrowth study
was carried out during spontaneous degassing accompanied by a gradual rise in pH. The experiment revealed that theprocesses and intensity of coccolith corrosion and subsequent overgrowth build-ups were inﬂuenced by a plethora ofdifferent factors, such as: 1) the pH and the associated seawater chemistry; 2) the mineral composition of the sediment;3) the presence of coccoliths within a protective substrate (fecal pellets, pores, pits); and 4) the presence/absence ofbacteria. Nannoplankton assemblages with etched or overgrown coccoliths showed that the observed relative abundancesof the taxa experienced alteration from the original compositions. Additionally, extreme pH oscillations may result inenhanced morphological changes that make coccoliths unidentiﬁable structures, and might even result in the absence of
coccoliths in the fossil record.
A comparison with actual fossil assemblages showed that all morphological types observed during this laboratory
experiment were also present in the fossil record. Our results suggest that the intensity of coccolith overgrowth can belinked with marine productivity in cases where the samples were deposited clearly above the lysocline and there wasno major input of terrigenous organic matter. We assume that the abundances of dissolution-resistant species and of
nannoplankton in the fossil record depend on a combination of primary abundance values and shifts induced by postmortem dissolution.

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Strontium isotope stratigraphy vs calcareous nannoplankton
datums in an epicontinental sea: A case study from the
Miocene Paratethys
Katarína Holcová
Institute of Geology and Palaeontology, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic; holcova@natur.cuni.cz

Filip Scheiner
Institute of Geology and Palaeontology, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic & Institute of Geology of the Czech
Academy of Sciences, Rozvojová 269, 165 00 Praha 6 Lysolaje, Czech Republic

Lukáš Ackerman, Jan Rejšek
Institute of Geology of the Czech Academy of Sciences, Rozvojová 269, 165 00 Praha 6 Lysolaje, Czech Republic

Václav Santolík
Institute of Geology and Palaeontology, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic & Institute of Geology of the Czech
Academy of Sciences, Rozvojová 269, 165 00 Praha 6 Lysolaje, Czech Republic

Biostratigraphic correlations in semi-enclosed epicontinental seas are affected by the many speciﬁc palaeoenvironmental
patterns that occurred in these marine basins, which do not have precise Recent equivalents. Therefore, the following
problems arise concerning the use of biostratigraphy and also strontium isotope stratigraphy (SIS): 1) the timing of
bioevents was dependent on speciﬁc palaeoenvironmental conditions that were limiting factors for the survival of theindex organisms in particular basins. This is especially true for basins that were located along communication gateways;
and 2) the speciﬁcity of seawater chemistry arising from varying fresh-water inputs, together with the rock weathering
intensity in the surrounding drainage areas (the weathering of carbonates can signiﬁcantly inﬂuence the 87Sr/86Sr ratio).
The aim of our study was to compare a large 87Sr/86Sr ratio dataset (100 values obtained from benthic and planktonic
foraminifera, otoliths and molluscs) with calcareous nannoplankton datums for the Upper Burdigalian–Serravallianinterval. As our study area, we selected the Eocene to Miocene system of European epicontinental seas called theParatethys, which was connected periodically with the surrounding oceanic domains. The following bioevents canbe identiﬁed in this interval in the selected study area: the last occurrence (LO) of Helicosphaera ampliaperta, theﬁrst occurrence (FO) and LO of H. waltrans, the FO of H. walbersdorfensis and, ﬁnally, the LO of Sphenolithus
heteromorphus. To conclude, the 87Sr/86Sr ratio was signiﬁcantly inﬂuenced by the characteristics of the weatheredrocks of the surrounding drainage areas in the studied epicontinental basins. Carbonate rocks can signiﬁcantly shift the87
Sr/86Sr ratio, while in areas with predominantly clastic rocks, 87Sr/86Sr ratios become closer to their oceanic values.

INA1859

Ultrastructure and taxonomy of the family Fasciculithaceae
Richard Howe
Ellington Geological Services, 1414 Lumpkin Road, Houston, TX 77043, USA; richard.howe@ellingtongeo.com

The family Fasciculithaceae are a group of Paleogene coccolith species with cylindrical, conical or discoidal coccoliths
comprising several vertically stacked cycles of elements radiating from a central point. I will describe the ultrastructureand high-level taxonomy in detail. In plan view, the cycles are strictly circular, and vary in height and width. The lowest
cycle is the column, the base of which is interpreted to be the proximal surface of the coccolith. Above the column, acycle of variable height and width is termed the ‘lateral cycle’. Above the lateral element cycle, is the highest cycle,
termed the ‘cone cycle’. The upper surface of the cone cycle is interpreted to be the distal surface of the coccolith.
Genera and species are differentiated by varying proportions and shapes of the three cycles. This basic ultrastructure isshared among species and genera in the Fasciculithaceae. The genera included here are Gomphiolithus, Lithoptychius,
Fasciculithus, Bomolithus, Tectulithus and Heliotrochus.
The genus Heliolithus has often been included in the Fasciculithaceae. Two vertically stacked circular cycles arepresent, which ﬂare outwards. Neither of these cycles is interpreted here as being a column. Heliolithus is probably
derived from Bomolithus or Tectulithus through loss of the column, which would make the two cycles homologous to
the lateral and cone cycles of fasciculithids. It is difﬁcult to assign either of the two cycles in Heliolithus to either thelateral or cone cycles of fasciculithids with any certainty. Because of this uncertainty in the exact relationship between
Heliolithus and the fasciculithids, species of Heliolithus are assigned to the family Heliolithaceae.

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Upper Cretaceous calcareous nannofossils from Gamba,
southern Tibet and their palaeoceanographic implications
Shijun Jiang, Yasu Wang
College of Oceanography, Hohai University, Nanjing 210098, China & Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai
519082, China; sjiang@hhu.edu.cn

Hong Su
College of Life Science and Technology, Jinan University, Guangzhou 510632, China

Richard W. Jordan
Faculty of Science, Yamagata University, Yamagata 990-8560, Japan

Calcareous nannofossils have proven to be a powerful tool in the division and correlation of Mesozoic and Cenozoic
marine strata due to their high abundance and robust morphology. Marine Jurassic, Cretaceous and Paleogene outcrops
are well exposed in southern Tibet. This part of the eastern Tethyan realm is characterised by high altitudes (usually
4000 m above sea level) and bare ground with very sparse to no vegetation for the entire year. The Chaqiela section in
the Gamba area is one of the classic sections for studying Mesozoic biostratigraphy and palaeoceanography, comprising
the Chaqiela, Lengqingre, Gangbacunkou, Jiubao and Zongshan Formations. It is noteworthy that, possibly due tolimited communication in the mid-20th century, when a massive survey was launched, there is a notable difference inthe deﬁnitions of the Chaqiela and Gangbacunkou Formations (including the Lengqingre, Xiawu Chubo and Jiubao
Formations) among different scholars. Even for the same authors, the positions of the formation boundaries are not
ﬁxed. Here, we present calcareous nannofossils from the black calcareous shales of the Lengqingre Formation, which
was previously dated as late Albian–Turonian.
Well-preserved and abundant calcareous nannofossil assemblages were observed and counted. The common taxa
include Biscutum constans, Discorhabdus ignotus, Eiffellithus turriseiffelii, Eprolithus ﬂoralis, Prediscosphaera
cretacea, Rhagodiscus achlyostaurion, Tranolithus orionatus, Watznaueria barnesiae and Zeugrhabdotus erectus. The
UC biozonation was applied based on the stratigraphical distribution of zonal markers in the section, such as Corollithion
kennedyi (base at 100.45 Ma, top at 94.64 Ma), Gartnerago segmentatum (base at 98.26 Ma) and Rhagodiscus asper(base at 94.30 Ma). The studied section spans UC0–UC3 (or NC10a–NC10b) and is thus actually Early Cenomanian inage (Late Cretaceous).
From the bottom to the top of the section, the calcareous nannoﬂora evolved from assemblages dominated byZeugrhabdotus erectus (Ze)–Discorhabdus ignotus (Di)–Biscutum constans (Bc)–Watznaueria barnesiae (Wb) to Bc–
Di–Wb–Ze and Wb–Ze assemblages. Zeugrhabdotus erectus, D. ignotus and B. constans are typically described as highproductivity/fertility indicators, while W. barnesiae is a typically oligotrophic species. The evolution of the calcareous
nannoplankton, quantiﬁed using nutrient and temperature indices (Herrle et al., 2003; Watkins, 2005), reﬂects an upsection decrease in primary productivity and an up-section warming during the Early Cenomanian, which is consistent
with the western Tethys region, as reported by Bottini and Erba (2018), which can be attributed to nutrient reduction
due to warming-related water-column stratiﬁcation. Most notably, the accompanying warming and eutrophication in
the lower part of the section correspond to the top of UC0 (or NC10a), suggesting the possible existence of Ocean
Anoxic Event 1d (OAE 1d), which, to date, has not been reported from this region. Acknowledgements: This work was
jointly funded by the National Natural Science Foundation of China (No. 41888101, 41672004) and the Southern Ocean
Science and Engineering Guangdong Laboratory (Zhuhai) Innovation Team Construction Project (No. 311021002).

INA1861

Coccolithophore abundance and degree of calcification andtheir contribution to particulate inorganic carbon in the South
China Sea
Xiaobo Jin, Chuanlian Liu, Juan Xu
State Key Laboratory of Marine Geology, Tongji University, Shanghai, China; evidently@163.com

Weifang Chen, Xianghui Guo

State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China

Particulate inorganic carbon (PIC) production and export to the deep ocean are important processes in water-column
carbonate cycling. Biochemical investigations have shown that modern seawater PIC in high-latitude eutrophic waters
is contributed by the marine calcifying algae––coccolithophores––which are constituted almost entirely of individualsof the species Emiliania huxleyi. This allows a predictability of the seawater PIC in these high-fertility regions based onsatellite remote sensing. However, the PIC in low-productivity surface waters, which accounts for 70% of the area of the
global ocean, the subsurface PIC maximum may not be well constrained by satellite.
Here, using samples from a biochemistry cruise in the South China Sea, we investigated seawater coccolithophorecell and coccolith abundances, the degree of E. huxleyi coccolith calciﬁcation, and PIC concentrations in the deep
chlorophyll-maximum layers, aiming to improve our understanding of PIC production in this low-productivity region.
Our results demonstrate the control of water-column nutrient levels on the geographical (horizontal) distribution of
Noelaerhabdaceae coccolithophores (E. huxleyi and Gephyrocapsa oceanica) in the investigated area, and also
indicate an insensitive response of degree of calciﬁcation in E. huxleyi coccoliths to carbonate chemistry. Although
Noelaerhabdaceae coccoliths are the major components of deep-sea-sediment carbonate, on average, they contributed<18% of the suspended PIC in the investigated seawater samples, indicating multiple sources for the highly variablesuspended PIC in the subsurface oligotrophic water. The production of Noelaerhabdaceae coccoliths greatly depends on
local environmental conditions, and this highlights the importance of ﬁeld investigations in low-fertility areas in orderto evaluate global PIC productivity.

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Extant coccolithophore distribution in the Mediterranean
Sea: A review
Roberta Johnson, Gerald Langer, Michael Grelaud
Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Barcelona, Spain; roberta.johnson@uab.cat

Patrizia Ziveri
Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Barcelona, Spain & Institució Catalana de Recerca i Estudis Avancats(ICREA), Barcelona, Spain

We present a systematic review of extant coccolithophore studies in the Mediterranean Sea. We compare coccolithophorecommunities and their ecological preferences and show the inﬂuence of environmental factors on their abundance. We
consider differences between speciﬁc biogeochemical regions in the Mediterranean Sea including the Adriatic, Aegean,
Cretan, Ionian, Ligurian, Balearic, Tyrrhenian and Alboran Seas, the Levantine Basin, as well as the Strait of Sicily and
the Gulf of Sidra. There will be a particular focus on the differences between the two major sub-basins––eastern andwestern––of the Mediterranean Sea. A total of 59 studies were selected, starting from 1990, 32 of which focus solely on
coccolithophores, while 27 examine the entire phytoplankton community.
The western Mediterranean Sea is underrepresented in coccolithophore research, with approximately 25% of allstudies conducted in this sub-basin (14 studies compared to 39 in the eastern basin). The Aegean and Adriatic Seas
are the most studied regions, followed by the Ionian and Tyrrhenian Seas (the most studied region in the western
Mediterranean). Summer is the most represented season (24 studies), followed by spring (20 studies), autumn (10) andwinter (eight studies). In the eastern Mediterranean, coccolithophores make up an average of 11% of the phytoplankton
community, whereas in the western basin, they make up 15.6% of the phytoplankton community (Alboran Sea). The mean
average abundance is greater in the eastern than in the western Mediterranean (2 x 104 L-1 ± 2.3 x 104 L-1 compared with
1.8 x 104 L-1 ± 1.6 x 104 L-1, respectively). The average maximum abundance is also greater in the eastern Mediterranean
Sea compared to the western (20.7 x 104 L-1 compared to 15.4 x 104 L-1).
The most common species across the Mediterranean Sea is Emiliania huxleyi, with other common genera including
Rhabdosphaera and Syracosphaera. There are many differences when reporting ﬁndings (cells per L-1, percent relative
abundance, percent frequency of occurrence, ﬂux), and many studies do not include raw data, making direct comparisons
difﬁcult. Studies that focus on the entire phytoplankton community may be underestimating coccolithophore abundanceand species diversity through the use of inappropriate counting methodology. Of the 14 studies in the western
Mediterranean, only six used inverted light microscopy, suggesting that abundance estimates for this region could beunderestimated. Further ﬁeld studies in this sub-basin using suitable methodologies could improve abundance andspecies diversity estimates.

INA1863

Middle Miocene to Pleistocene nannofossil biostratigraphyof the North Atlantic: Preliminary results from IODP
Expedition 395C, Reykjanes Ridge
Boris-Theofanis Karatsolis
Department of Earth Sciences, Uppsala University, Villavägen 16, 754 30 Uppsala, Sweden; boris.karatsolis@geo.uu.se

Anita Di Chiara
Istituto Nazionale di Geoﬁsica e Vulcanologia (INGV), Via di Vigna Murata 605, 00143 Rome, Italy

Sara Satolli
Department of Engineering and Geology, University of Chieti-Pescara, Via dei Vestini 31, 66100 Chieti Scalo, Italy

Sarah Friedman
Department of Geology and Geography, Georgia Southern University, 68 Georgia Avenue, Statesboro, GA 30458, USA

Expedition 395C/395 scientific participants
https://iodp.tamu.edu/scienceops/precruise/reykjanes/participants.html

During the summer of 2021 (June–August), IODP Expedition 395C operated south-west of Iceland and drilled a transect
eastwards of the modern Mid-Atlantic Ridge (between 20 and 30ºW) at a latitude of ~60ºN. Sedimentary sections
reaching the basaltic basement were successfully recovered from four sites––Holes U1555H, U1563A, U1554E andU1562A. The age of the acoustic basement, estimated from magnetic anomalies, varied from 14.2 Ma for the site
located furthest from the ridge (U1562) and 2.8 Ma for the site most proximal to the ridge (U1555). Here, we present
a preliminary Middle Miocene to Pleistocene nannofossil biostratigraphy for the recovered sediments. Nannofossils
were abundant in most samples, with moderate to good preservation that generally improved towards the Late Pliocene
to Pleistocene. In total, 28 bioevents were identiﬁed and assigned an age based on the Neogene time-scale of Rafﬁ etal. (2020). Several biohorizons could be identiﬁed across the sites, including the top occurrence of Reticulofenestra
pseudoumbilicus at 3.82 Ma (base of Zone NN16 of Martini, 1971), the top occurrence of Helicosphaera sellii at
1.24 Ma, the top occurrence of Pseudoemiliania lacunosa at 0.43 Ma (base of Zone NN20) and the base occurrenceof Emiliania huxleyi at 0.29 Ma (base of Zone NN21). The top occurrence of Discoaster brouweri at 1.93 Ma was
only observed in Hole U1555H, due to this species’ low abundance and intermittent presence. Most of the identiﬁed
bioevents demonstrated very good correlation with the preliminary Late Pliocene to Pleistocene magnetostratigraphy.
However, the top of R. pseudoumbilicus (Early Pliocene) always appeared to be older than 3.82 Ma based on the ages
suggested by the preliminary magnetostratigraphy. This offset could be explained by an earlier extinction (therefore anolder age for this event) or very low abundances of this species towards its last occurrence at this latitude in the North
Atlantic. Further investigation of the nannofossil and foraminifera assemblages will help us scrutinise and understandsuch diachronicities and improve our understanding of the Miocene to Pleistocene North Atlantic biostratigraphy.
References
Martini, E. 1971. Standard Tertiary and Quaternary calcareous nannoplankton zonation. In: A. Farinacci (Ed.). Proceedings of the 2nd International
Conference on Planktonic Microfossils, Roma 2:739–785.
Rafﬁ, I., Wade, B.S. & Pälike, H. 2020. The Neogene Period (Chapter 29). In: F.M. Gradstein, J.G. Ogg, M.D. Schmitz & G.M. Ogg (Eds). GeologicalTime Scale 2020 2:1141–1215.

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Cretaceous–Paleogene calcareous nannofossils fromInternational Ocean Discovery Program Expedition 392 to
the Agulhas Plateau, south-western Indian Ocean
Denise K. Kulhanek
Institute of Geosciences, Christian-Albrechts-University of Kiel, Ludewig-Meyn-Straße 10–14, 24118 Kiel, Germany; denise.kulhanek@ifg.unikiel.de

Odysseas A. Archontikis
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK

Jens O. Herrle
Institute of Geosciences, Goethe-University Frankfurt, Altenhoeferallee 1, 60438 Frankfurt am Main, GermanyPeter K. Bijl
Department of Earth Sciences, Utrecht University, Princetonlaan 8A, 3584 CB Utrecht, Netherlands

Ashley M. Burkett
Boone Pickens School of Geology, Oklahoma State University, 103C, 105 Noble Research Center, Stillwater, OK 74078, USA

Jason J. Coenen
Geology and Environmental Geosciences, Northern Illinois University, Davis Hall 312, 218 Normal Road, DeKalb, IL 60115, USA

Edoardo Dallanave
Department of Geosciences, University of Bremen, Klagenfurter Straße 2-4, 28359 Bremen, Germany

Courtney J. Sprain
Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL 32611, USA

Sietske J. Batenburg
Department of Earth and Ocean Dynamics, University of Barcelona, Martí i Franqués, 08028 Barcelona, Spain

Thomas Westerhold
MARUM, Center for Marine Environmental Sciences, University of Bremen, Leobener Straße 8, 28359 Bremen, Germany

Gabriele Uenzelmann-Neben
Department of Geosciences, Geophysics Section, Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Am Alten Hafen 26,27568 Bremerhaven, Germany

Steven M. Bohaty
Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 234-236, 69120 Heidelberg, Germany

Laurel Childress
International Ocean Discovery Program, Texas A&M University, 1000 Discovery Drive, College Station, TX 77845, USA

IODP Expedition 392 Scientific Party
International Ocean Discovery Program (IODP) Expedition 392 cored three sites on the Agulhas Plateau and one site in
the Transkei Basin to address questions regarding the origin and timing of the emplacement of the Agulhas Plateau, aswell as to examine Southern Ocean climate history and the opening of oceanic gateways from the Cretaceous throughthe Paleogene. The age models for the sites relied primarily on calcareous nannofossils and magnetostratigraphy, with
dinoﬂagellates providing key events for some intervals, and additional constraints from planktonic foraminifera anddiatoms. Site U1579, located in a depression on the central Agulhas Plateau, recorded a nearly continuous section
dated Santonian to earliest Miocene. Dinoﬂagellates provided the age control for the zeolitic sandstone and siltstone
with glauconite at the base of the cored section. Above this, nannofossils were common to abundant and moderately
preserved in the Upper Santonian to Maastrichtian calcareous chalks, with the assemblages showing Southern Ocean
afﬁnities. Paleogene nannofossils were abundant and moderately to well preserved. Sedimentation rates were the lowest
in the Eocene, which included either condensed intervals or hiatuses. Nannofossils were well preserved in the Oligocene,INA1865

with the assemblages consisting of primarily mid-latitude species with occasional incursions of cold-water taxa. Site
U1580 was located on the southern Agulhas Plateau, adjacent to a basement high. Cretaceous–Cenozoic sedimentation
at this site was interrupted by several unconformities, and the lowermost part of the cored interval was interspersed withbasalt layers interpreted as sills. The oldest sediment was likely uppermost Cenomanian in age. Overlying the shallowest
basalt were a Coniacian–Santonian silt- and sandstone with varying proportions of zeolites, glauconite and carbonate.
Sedimentation rates were very high (~10 cm/kyr) during this time. Much of the Lower Campanian and mid-Maastrichtian
were missing at this site. The Paleocene nannofossils were moderately well preserved and suggested a continuous
section with sedimentation rates of 1.5 cm/kyr. The sedimentation rates increased in the Late Paleocene to Early Eocene,and nannofossils were quite well preserved through the Paleocene–Eocene Thermal Maximum and in the Lower Eocene
chalk/ooze. Site U1581 in the Transkei Basin included a thick section of Upper Campanian to Maastrichtian mudstone
with occasional sandstone beds. Nannofossils were sparse, but very well preserved through much of this interval,
although the preservation decreased with depth, concomitant with increasing siderite. The Cretaceous assemblages
included both Southern Ocean and mid-latitude taxa. Reworking was common throughout the Cenozoic and this interval
was also interspersed with hiatuses, especially in the Eocene and Miocene. Sedimentation appears to have been more
continuous from the latest Miocene to the present, with sedimentation rates of ~2.8 cm/kyr. Site U1582, cored on thenorthern Agulhas Plateau, included only ~40 m of ooze and siliciclastic sediments overlying the basement. Manganese
nodules were common, and the section was highly condensed, with at least 70 Myr represented. Future work will reﬁnethe age models for each site to provide a framework for the palaeoclimatic and palaeoceanographic studies planned by
the expedition science party members.

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Distinct physiological responses of Coccolithus braarudii
life-cycle phases to light intensity and nutrient availability
Gerald Langer
Institute of Environmental Science and Technology (ICTA), Universitat Autònoma de Barcelona (UAB), 08193 Bellaterra, Spain; Gerald.Langer@
uab.catVun Wen Jie, Dorothee Kottmeier, Serena Flori, Daniela Sturm, Joostde Vries
The Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK

Glenn M. Harper
Plymouth Electron Microscopy Centre, Brunel, Drake Circus, Plymouth PL4 8AA, UK

Colin Brownlee, Glen Wheeler
The Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK

Coccolithophores feature a haplo-diplontic life-cycle comprised of diploid cells producing heterococcoliths and haploidcells producing morphologically different holococcoliths. These life-cycle phases of each species appear to havedistinct spatial and temporal distributions in the oceans, with the heavily calciﬁed heterococcolithophores (HET) often
being more prevalent in winter and at greater depths, whilst the lightly calciﬁed holococcolithophores (HOL) are moreabundant in summer and in shallower waters. The haplo-diplontic life-cycle may therefore allow coccolithophores
to expand their ecological niche, switching between life-cycle phases to exploit conditions that are more favourable.
However, coccolithophore life-cycles remain poorly understood, and fundamental information on the physiologicaldifferences between life-cycle phases is required if we are to better understand the ecophysiology of coccolithophores.
In this study, we have examined the physiology of the HET and HOL phases of the coccolithophore Coccolithus
braarudii in response to changes in light and nutrient availability. We found that the HOL phase was more tolerant tohigh light intensity than the HET phase, which exhibited defects in calciﬁcation at high irradiances. The HET phaseexhibited defects in coccolith formation under both nitrate and phosphate limitation, whilst no defects in calciﬁcation
were detected in the HOL phase. The HOL phase grew to a higher cell density under phosphate-limitation than nitratelimitation, whereas no difference was observed in the maximum cell density reached by the HET phase at these nutrient
concentrations. The HET cells grown under a light:dark cycle divided primarily in the dark and in the early part of thelight phase, whereas the HOL cells continued to divide throughout the 24-h period. The physiological differences may
contribute to the distinct biogeographical distributions observed between the life-cycle phases, with the HOL phasepotentially being better adapted to high-light, low-nutrient regimes, such as those found in seasonally stratiﬁed surface
waters.

INA1867

Oceanic temperature and pCO2 reconstruction during
the Pliocene in the Caribbean Sea (ODP Site 999) using
coccolith geochemistry
Goulwen Le Guevel, Fabrice Minoletti
Sorbonne Université, ISTeP, Paris, France; goulwen.le_guevel@sorbonne-universite.fr

Michael Hermoso
Université du Littoral Côte d’Opale, Laboratoire d’Océanologie et de Géosciences, Wimereux, France

The Pliocene (5.33–2.58 Ma) is one of the key periods cited by the IPCC as a geological analogue of anthropogenic
climate change. The global climate during this period was indeed comparable with modelling predictions for the near
future––sea-surface temperatures (SSTs) were 3ºC warmer than today and atmospheric pCO2 was 1 to 1.5 times higher
than preindustrial values.
These two major climate parameters (SSTs and pCO2) are usually assessed using proxies involving measurements
made on both the organic matter produced by coccolithophores (alkenones) and the calcite of foraminiferal tests. Our
approach was to use a unique archive––the coccoliths––for the determination of both SSTs and pCO2. Coccoliths are avery promising substrate to analyse for palaeoclimatic studies because they calcify in the uppermost water-column andbecause their isotopic ratios are sensitive to both photosynthesis and calciﬁcation (Hermoso et al., 2016). Therefore,
these isotopic ratios give us physiological and metabolic information about coccolithophores of the past.
After microseparation of the coccoliths into various size fractions (Minoletti et al., 2009), we used oxygen isotopic
ratios for the SST calculations. We also derived pCO2 from the difference in δ13C between the small and large coccoliths
fractions following a recently calibrated CO2 proxy (Godbillot et al., 2022).
The results obtained from samples spanning the entire Pliocene interval (ODP 999A, Kogi Rise in the Caribbean Sea
at 13ºN and DSDP Site 516, Rio Grande Rise in the South Atlantic at 30ºS) showed an increase in SSTs between 5 and 4
Ma in the Caribbean Sea from 26 to 31ºC, in contrast to results from the south-eastern Atlantic, where the surface waters
freshened during that period. From 4 to 2.5 Ma, both temperature trends were reversed, with a notable decrease in SSTs
in the Caribbean Sea from 31 to 27ºC. This is consistent with published results (Karas et al., 2017). Our pCO2 values arein agreement with published datasets (Rae et al., 2021) and show small variations throughout the Pliocene (between 310
and 375 ppmv in the whole interval). These results conﬁrm that the biogeochemistry of coccoliths has a great potential
for deep-time palaeoclimate reconstruction.
References
Godbillot, C., Minoletti, F., Bassinot, F. & Hermoso, M. 2022. Parallel between the isotopic composition of coccolith calcite and carbon levels acrossTermination II: Developing a new paleo-CO2 probe. Climate of the Past, 18: 449–464.
Hermoso, M., Chan, I.Z.X., McClelland, H.L.O., Heureux, A.M.C. & Rickaby, R.E.M. 2016. Vanishing coccolith vital effects with alleviated carbon
limitation. Biogeosciences, 13: 301–312.
Karas, C., Nürnberg, D., Bahr, A., Groeneveld, J., Herrle, J.O., Tiedemann, R. & deMenocal, P.B. 2017. Pliocene oceanic seaways and global climate.
Scientiﬁc Reports, 7: 39842.
Minoletti, F., Hermoso, M. & Gressier, V. 2009. Separation of sedimentary micron-sized particles for palaeoceanography and calcareous nannoplankton
biogeochemistry. Nature Protocols, 4: 14–24.
Rae, J.W.B., Zhang, Y.G., Liu, X., Foster, G.L., Stoll, H.M. & Whiteford, R.D.M. 2021. Atmospheric CO2 over the past 66 million years from marinearchives. Annual Review of Earth and Planetary Sciences, 49: 609–641.

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Evolution of Miocene calcareous nannofossil assemblages
and palaeoceanographic research on the South China Sea
Chuanlian Liu, Guanyu Lin, Ruixue Gong, Hui Zhang
State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China; liucl@tongji.edu.cn

We will present Miocene calcareous nannofossil biostratigraphic events, assemblages and morphological parametersfrom International Ocean Discovery Program (IODP) Site 1501 in the northern South China Sea. Firstly, we divided thestrata using the biostratigraphic events of the Miocene to determine the depth–time relationship. Secondly, we quantiﬁed
the Miocene nannofossil assemblages, including the ratio of the abundance of nutrient-rich and nutrient-poor species(N ratio) to reconstruct the marine palaeoproductivity. In the Miocene, the periods of high productivity were 23–12.5
Ma and 6–5 Ma, while the period of low productivity was 12.5–6 Ma. Interestingly, there was local low productivity
at 16–14.5 Ma, while local productivity was high 9.9–8.8 Ma. In addition, we compared the N ratio of the calcareous
nannofossils with global phenomena, such as biogenic blooms, carbon isotope shifts and the carbonate crash in the
Miocene. It was found that the biogenic bloom period shows good correspondence with the N ratio 6–5 Ma and 9.9–8.8
Ma, with the N ratio indicating high productivity environments at these times. The carbon isotope ratio of seawater wascontinuously heavier 23–16 Ma, when the N ratio indicated high productivity. At 13.5–6 Ma, the carbon isotope ratios
were continuously lighter, while the N ratio indicated low productivity. Therefore, there is a clear correlation between
marine productivity and the carbon isotope signal. At 9.9–8.8 Ma, a carbonate crash was indicated by a signiﬁcantdecrease in the carbonate content in the sediments. At the same time, the N ratio suggested a nutrient-rich environment.
We also quantiﬁed changes in the Miocene coccolith morphological parameters, including length, thickness and weight,
which all showed very similar patterns. The morphological parameters often had lower values when the N ratio washigher. Thus, a high-productivity environment may lead to smaller, thinner and lighter coccolith morphologies. In
comparing reconstructions of atmospheric CO2 concentrations with coccolith morphology, it was found that atmospheric
CO2 concentrations peaked during the Middle Miocene Climatic Optimum (MCO), at which time, coccolith length wasat its shortest. On the whole, coccolith length is negatively correlated with atmospheric CO2 concentrations. This may
be because a high concentration of atmospheric CO2 promotes the dissolution of coccoliths, but it is worth noting that
atmospheric CO2 concentrations were higher in the Early Miocene, and coccolith length tended to be longer at that time.
This shows that atmospheric CO2 may also promote calciﬁcation when atmospheric CO2 concentrations are moderate.

INA1869

The Lorca Basin revisited: How integrated stratigraphy canhelp resolve long-standing controversies
Francesca Lozar, Enrico Nallino, Gabrielle Viggiani
Department of Earth Sciences, Università degli Studi di Torino, Torino, Italy; francesca.lozar@unito.it

Hugo Corbí Sevila, Jesus Soria Mingorance
Department of Earth and Environmental Sciences, Universidad de Alicante, Spain

Alan Deino
Berkeley Geochronology Center, Berkeley, CA, USA

Luis Gibert Beotas
Department of Mineralogy, Petrology and Applied Geology, Universidad de Barcelona, Spain

Evaporitic deposition was widespread and voluminous during the Late Miocene in the Mediterranean Basin. These
deposits can be correlated regionally to marginal basins with strikingly similar depositional ages. However, the age of
the Upper Miocene sediments of the Lorca Basin in southern Spain remains controversial, with the pre-evaporitic andevaporitic deposits having been variously assigned to the Tortonian and the Messinian.
We performed an integrated study of the Varied Member of the Serrata Formation from the La Serrata section, basedon sedimentology, calcareous plankton micropalaeontology, magnetostratigraphy and radiochronology. Preliminary
data indicate that the succession was deposited during the Messinian on the basis of the calcareous nannofossil andforaminifera assemblages.
The ﬁnding of Reticulofenestra rotaria from the base of the Varied Member indicates an age not greater than 7.4
Ma. The ﬁrst consistent occurrence, in the middle part of the section, of Turborotalita multiloba (an endemic Messinian
foraminiferal taxon) concurrently with Neogloboquadrina acostaensis (sinistral coiling) in an interval with reverse
magnetic polarity suggests a correlation with the UA15–17 cycles identiﬁed by Sierro et al. (2001) in the Perales
section (Sorbas Basin, Spain). Two dispersed tephra layers identiﬁed at the base of the section contained volcanic glass
and a mineral assemblage suitable for 40Ar/39Ar dating. These layers occur just below the occurrence of Turborotalita
multiloba and the 40Ar/39Ar dating of these tuffs is underway to test this age interpretation.
The available data permit a reconstruction of the characteristics of the water-column immediately before thedeposition of the gypsum of the Messinian Salinity Crisis. The environment was evidently eutrophic, as also suggested
by a great abundance of diatoms.

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Nutrient forcing on the late Middle Eocene to Early
Oligocene (~40–31 Ma) evolution of the coccolithophore
Reticulofenestra (Order Isochrysidales)
Ruigang Ma
State Key Laboratory of Marine Geology, Tongji University, Shanghai, China; maruigang@tongji.edu.cn

Marie-Pierre Aubry
Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, USA

David Bord
Ellington Geological Services, 1414 Lumpkin Road, Houston, TX 77043, USA

Chuanlian Liu
State Key Laboratory of Marine Geology, Tongji University, Shanghai, China

The ﬁrst size reduction (FSR) in coccolithophores of the Order Isochrysidales, which occurred in the Early Oligocene(~32 Ma), is of great signiﬁcance for understanding the Lilliput effect that has affected all coccolithophores from theLate Eocene to this day, and is generally interpreted as reﬂecting a global pCO2 decline. Here, we offer a complementarymechanism based on the results of a comprehensive morphometric analysis of the coccoliths of Reticulofenestra species
that lived during late Middle Eocene to Early Oligocene (~40–31 Ma), using marine sediments from the South Atlantic
Ocean. The results show increased size and decreased abundance of the large group during the Late Eocene and Early
Oligocene, leading to the disappearance of large Reticulofenestras at the FSR and a concurrent decrease in the size
variability of the small to medium coccoliths, in which the diameter of the central opening had become very reduced. We
have interpreted these results in light of an ecological model designed to link coccolith morphology and trophic strategy.
In sunlit oceanic waters, the small- to medium-sized, r-selected coccolithophores with smaller central openings lived
in deeper, nutrient-rich waters, where they did not rely much on mixotrophy. The larger, K-selected species with larger
central openings lived in the oligotrophic surface waters where they strongly relied on mixotrophy. On this basis, we
propose that the FSR is the mid-term result of the environmental destabilisation that occurred at ~35.5 Ma, caused by
the expansion of eutrophic environments following the establishment of overturning circulation in the Atlantic Ocean.

INA1871

Coccolithophore physiology and molecular mechanism
response to the seawater Mg/Ca ratio
Xiaoxu Ma, El Mahdi Bendif, Craig Dedman, Rosalind E.M. Rickaby
Department of Earth Sciences, University of Oxford, South Parks Road, OX1 3AN, UK; xiaoxu.ma@exeter.ox.ac.uk

Coccolithophores are calcifying unicellular phytoplankton that are sensitive to environmental change. As the mostubiquitous ion and nutrient element, Mg2+ is essential for enzyme functionalisation, ion homeostasis and photosynthesis.
In addition, Mg also has the potential to inhibit mineral growth in inorganic calcite and raises the saturation state needed
for the precipitation of calcite. The primary mineralogy of inorganic carbonates in the high-Mg/Ca modern ocean isaragonite. It is unknown, however, whether an increasing Mg content in the ocean relative to Ca, as has occurred overthe last 60 million years, may also interfere with calcite biomineralisers, particularly coccolithophores, which calcify
intracellularly and have reduced in size over this same time-scale.
Through this study, we are aiming to have a comprehensive understanding of the Mg concentration interferencewith coccolithophore physiology and calciﬁcation abilities. We cultured six strains that represent four coccolithophore
species, including over-calciﬁed and regularly-calciﬁed Gephyrocapsa huxleyi, G. oceanica, Coccolithus braarudii
and C. pelagicus, under a range of Mg/Ca ratios. For the physiology response, we evaluated their cell adaptation andcalciﬁcation sensitivities under different Mg concentrations by measuring the growth rate, chlorophyll concentration,
morphology and calciﬁcation level. For all strains, we found that the lowest Mg/Ca ratio could limit growth, with nosigniﬁcant malformations observed in the coccoliths. Gephyrocapsa huxleyi strains appeared to exert the strongest
control over the chemistry at the site of calciﬁcation, as they were still able to calcify under extreme Mg concentrations.
However, more malformed and incomplete coccoliths were observed with increasing Mg. Gephyrocapsa oceanica canmaintain its calciﬁcation ability across the Mg/Ca range, except under extremely high Mg concentrations. Coccolithus
spp. were more vulnerable than other species because their growth was more reduced at medium Mg/Ca ratios,reaching complete growth inhibition at higher Mg concentrations. To understand the molecular mechanism behind thephysiological adaptation, we assessed the stoichiometry of one strain of G. huxleyi. We found that the Mg/Ca ratio incells increased simultaneously with a rise in the ambient Mg/Ca ratio, while the Mg partitioning coefﬁcient decreased.
The elemental composition of this strain reﬂected its malformation status and chlorophyll content. Further proteomic
analysis will be performed in order to examine the detailed molecular mechanism of different calciﬁcation abilities in
G. huxleyi.

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Oligo-monospecific assemblage of calcareous
nannoplankton in response to the Messinian
palaeoceanographic setting: Insights from the Monte dei
Corvi section (central Italy)
Alan Maria Mancini, Francesca Lozar, Rocco Gennari
Dipartimento di Scienze della Terra, Universita degli Studi di Torino, Torino, Italy; alanmaria.mancini@unito.it

Savannah Myers, Alessandra Negri
Dipartimento di Scienze della Vita e dell’Ambiente, Università Politecnica delle Marche, Ancona, Italy

During the Messinian, tectonic uplift in the palaeo-Gibraltar Strait resulted in a progressive reduction in waterexchange between the Atlantic and the Mediterranean, promoting a sluggish thermohaline circulation and resulting inperiodic oxygen starvation at the seaﬂoor. Before the Messinian Salinity Crisis (MSC, 5.97–5.33 Ma), the hemipelagic
sedimentation in the Mediterranean Basin was controlled by changes in Earth’s orbital parameters, and was usuallycharacterised by the rhythmic deposition of organic-rich marls, intercalated with white marls, diatomites or limestones.
The organic-rich marls, often termed ‘sapropels’, were thought to be deposited during precession-minima phases(insolation maxima), when the seaﬂoor suffered oxygen deﬁciency. A clear example of precession-driven sedimentation
crops out in the Monte dei Corvi section (Ancona, central Italy), where sapropels are intercalated with white limestones.
Here, we present a high-resolution study of calcareous nannofossils (CN), coupled with a petrographic investigation,
conducted over four sedimentary cycles (from 6.55 to 6.48) of the Monte dei Corvi section, in order to better constrain
the palaeoceanographic conditions that promoted the deposition of the sapropels and limestones. The CN assemblage
recorded in the sapropels is dominated by taxa (Discoaster spp. and Sphenolithus spp.) that were able to proliferate
in the lower photic zone, when the nutricline shoaled in the photic zone and a deep chlorophyll maximum occurred.
The sapropels are ﬁnely laminated, with abundant small pyrite inclusions and lacking macrobioturbation. Both themicropalaeontological and petrographic features point to a strongly stratiﬁed water-column during the sapropel
deposition, a condition that prevented oxygen diffusion at the seaﬂoor through thermohaline circulation. Conversely,
the limestone beds were nannofossil oozes, characterised by either oligospeciﬁc or monospeciﬁc CN assemblages,
composed of Umbilicosphaera jafari and/or Reticulofenestra antarctica and/or Calcidiscus leptoporus. The limestone
beds are ﬁnely laminated, especially at the top, and the lamination is made by the alternation of white (fecal pellets
with nannofossils) and brown (mainly terrigenous) laminae. The low diversity of the CN assemblages in the limestone
deposits suggests extreme environmental conditions in the upper water-column, probably related to high salinity, colder
temperatures and eutrophication. Therefore, we infer that the limestone beds were deposited in response to a recoveryof the mixing processes in the photic zone, which stimulated CN productivity and exported their remains to the seaﬂoor.
A detailed comparison with CN assemblages of about the same age, reported from south-eastern Spain (Sorbas Basin),indicated the same features, but occurring in different lithofacies. These ﬁndings suggest that the palaeoceanographic
conditions responsible for the sapropel deposition differed across the various Mediterranean sub-basins. Indeed, in the
Sorbas Basin, the onset of the sapropel coincides with a precession-driven cold phase. The conclusions reached could be
useful for better constraining, and potentially predicting, the Mediterranean deoxygenation trend in response to current
climate change.

INA1873

Calcareous nannofossils across the Campanian–
Maastrichtian high-productivity system of Aderet, Shefela
Basin, Israel
Sara Marconato, Sigal Abramovich
Ben Gurion University of the Negev, Israel; saramarc@post.bgu.ac.il

Nicolas Rudolph Thibault
IGN, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark

Sarit Ashckenazi-Polivoda
Dead Sea and Arava Science Center, Israel

In the Late Cretaceous, the Levant area was characterised by a large upwelling zone, as now witnessed by the organicrich carbonates of the Mishash and Ghareb Formations. Previous stratigraphical and palaeoceanographical studies of
the Campanian to Maastrichtian deposits in this area showed prominent facies variation, from fully oxygenated toanoxic conditions across N–S and E–W transects. The Aderet core was drilled in the depocenter of the Shefela Basin,
Israel, considered to be a deeper distal position in the upwelling belt. Because the Aderet core has so far delivered
unique tropical sea-surface temperature reconstructions for the Santonian to Maastrichtian, based on TEX86, this corerequires a precise stratigraphic framework and age-model. Until now, the stratigraphy and age-model had been basedon foraminifera only, but the position of the Campanian/Maastrichtian boundary remained unclear. Here, we present thecalcareous nannofossil biostratigraphy of the Aderet borehole at a resolution of 5 m––approximately equivalent to thatused for the planktonic foraminifera. Due to the high percentages of total organic carbon (TOC), varying between 5 and20%, we adopted a protocol to oxidise the organic matter prior to preparing the nannofossil slides. A comparison between
slides made with and without the adopted protocol showed that the protocol signiﬁcantly improved the abundances andobservation of the nannofossils.The core can be ascribed to CC20 to CC25a sensu Perch Nielsen (1985) and UC14b to
UC19 sensu Burnett et al. (1998). Our study allowed us to revise the previous age-model by integrating the calcareous
nannofossil and planktonic foraminifera biohorizons, and using the Bacon modelling approach. Accordingly, the age ofthe borehole extended from 79.2 Ma to 69.4 Ma and the Campanian/Maastrichtian boundary was signiﬁcantly revised toa depth between 361 m, close to the base of Pseudoguembelina palpebra, and 332 m, near the top of Uniplanarius triﬁdus(in contrast to previous studies that positioned this boundary at 452 m). In addition, preliminary palaeoecological results
conﬁrm the constant presence of eutrophic to mesotrophic calcareous taxa (Biscutum constans, Placozygus ﬁbuliformis,
Zeugrhabdotus group, Cervisiella saxea) and delineate a response to the general cooling trend of the Late Campanian–
Early Maastrichtian, expressed by increases in Arkhangelskiella cymbiformis, Ahmuellerella octoradiata, A. regularis,
Cribrosphaerella ehrenbergii, Prediscosphaera cretacea and Micula staurophora and changes in biodiversity.
References
Ashckenazi-Polivoda, S., Titelboim, D., Meilijson, A., Almogi-Labin, A., & Abramovich, S. 2018. Bathymetric trend of Late Cretaceous southern
Tethys upwelling regime based on benthic foraminifera. Cretaceous Research, 82: 40–55.
Burnett, J.A. 1998. Upper Cretaceous. In: P.R. Bown (Ed.). Calcareous nannofossil biostratigraphy. London: Chapman and Hall, 132–199.
Eshet, Y. & Moshkovitz, S. 1995. New nannofossil biostratigraphy for Upper Cretaceous organic-rich carbonates in Israel. Micropaleontology, 321–
341.
Meilijson, A., Ashckenazi-Polivoda, S., Illner, P., Speijer, R.P., Almogi-Labin, A., Feinstein, S. & Abramovich, S. 2018. From phytoplankton to oil
shale reservoirs: A 19-million-year record of the Late Cretaceous Tethyan upwelling regime in the Levant Basin. Marine and Petroleum Geology,
95: 188–205.
Perch Nielsen, K. 1985. Mesozoic calcareous nannofossils. In: H.M. Bolli, J.B. Saunders & K. Perch-Nielsen (Eds). Plankton stratigraphy: Volume 1.
Planktonic foraminifera, calcareous nannofossils and calpionellids. Cambridge: Cambridge University Press.
Shawar, L., Halevy, I., Said-Ahmad, W., Feinstein, S., Boyko, V., Kamyshny, A. & Amrani, A. 2018. Dynamics of pyrite formation and organic matter
sulfurization in organic-rich carbonate sediments. Geochimica et Cosmochimica Acta, 241: 219–239.

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Messinian–Pliocene chronostratigraphy andpalaeoceanography of IODP Site 1387: The calcareous
nannofossil washing–winnowing effectLaura Martín García, José-Abel Flores, Francisco J. Sierro
Department of Geology, University of Salamanca, Salamanca, Spain; lauramaga@usal.es

Barbara Balestra
American University, Environmental Science Department, 20016 Washington DC, USA & National Museum of Natural History, Smithsonian,
Paleobiology Department, 20560 Washington DC, USA & University of California, Santa Cruz, Institute of Marine Sciences, 95064 Santa Cruz, CA,
USA

The Messinian Salinity Crisis was one of the most important episodes in the history of the Mediterranean, with a relevant
impact on the ocean, particularly in the Atlantic. From Miocene–Pliocene material retrieved from IODP Site 1387,
located in the Gulf of Cádiz, we performed a biostratigraphical review and an environmental reconstruction, taking into
account surface water temperatures, nutrient availability and productivity.
In the analysed samples, several standard CN biozonation events were identiﬁed and calibrated, including the highest
occurrence (HO) of Amaurolithus ampliﬁcus, lowest occurrence (LO) of Ceratolithus acutus armatus, LO of C. cristatus
and LOs of Discoaster asymmetricus and D. tamalis, allowing us to reﬁne the previous biostratigraphy.
Additionally, we realised a sedimentological study on the core, identifying washing–winnowing episodes in samples
resulting from contour currents. These samples were characterised by abrupt decreases in the nannofossil content andan increase in sand-sized particles. The most relevant washing–winnowing episode was dated at between 5.62 and 5.38
Ma, coinciding with the end of the Messinian Salinity Crisis.
This preliminary study allows us to conclude that, during the Late Messinian in the Gulf of Cadiz, the surface waters
were warm and oligotrophic, related to the Mediterranean–Atlantic disconnection during the salinity crisis. Curiously,
our data indicate that contourite currents were also produced during the salinity crisis. Later, during the Pliocene, thesurface-waters were colder and eutrophic, as a result of the Mediterranean–Atlantic connection.

INA1875

Weakening of the biological pump induced by anannoplankton crisis during the Early Toarcian Oceanic
Anoxic Event
Wolfgang Ruebsam
Department of Organic and Isotope Geochemistry, Institute of Geoscience, University of Kiel, Germany

Emanuela Mattioli
Université Lyon, UCBL, ENSL, UJM, CNRS, UMR 5276 LGL-TPE, F-69622 Villeurbanne, France, & Institut Universitaire de France, Paris,
France; emanuela.mattioli@univ-lyon1.fr

Lorenz Schwark
Department of Organic and Isotope Geochemistry, Institute of Geoscience, University of Kiel, Germany & WA-OIGC, Curtin University, Perth,
Australia

Severe environmental changes occurred during the Early Toarcian (Early Jurassic, ~183 Ma) related to the rising atmospheric CO2 concentration and associated changes in ocean alkalinity and seawater temperatures. Such perturbations
directly or indirectly (i.e. via ocean-water stratiﬁcation and nutrient delivery to the surface waters) impacted the marine
primary producers. Changes in the phytoplankton community structure, in turn, affected the marine food web, the biological pump and thereby the entire marine ecosystem and carbon cycling. Recently, this scenario has been challenged
thanks to the recovery in sediments of imprints of coccoliths on organic materials, originating from the dissolution of
CaCO3 due to the presence of high amounts of organic matter leading to acidic pore waters during diagenesis.
We show here new data from the core FR-210-078 (Lorraine Basin), where rather low organic carbon accumulation
rates have been estimated. This observation is substantiated by a reduced export efﬁciency of organic carbon to the sediment, caused by a drastic decline in the abundance of mineral ballast (i.e. nannoplankton-derived calcite), due to a major
decrease in the calciﬁcation potential of the coccolithophores, and in calcareous nannofossil ﬂuxes. Besides this decline
in primary carbonate production, a drop in both abundance and size was documented for the fecal pellets. A net reduction
in mineral (i.e. calcite) ballast led to weakening of the sinking speed of particulate organic matter that then became more
prone to biodegradation. The reduced organic-carbon accumulation rates are here interpreted as reﬂecting a weakeningof the biological pump. These new data substantiate the role of organic-matter preservation as a major factor controllingthe formation of black shales during the Early Toarcian, as well as the key role played by calcareous nannoplankton in
the carbon cycle during past dramatic climatic events.

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The coccolithophore community of the Sargasso Sea
Josué G. Millán, Amos WinterIndiana State University, Terre Haute, Indiana, USA; jmillan1@sycamores.indstate.edu

Richard W. Jordan
Yamagata University, Yamagata, Japan

Jeremy R. Young
University College London, London, UK

Leocadio Blanco-Bercial, Rod Johnson
Bermuda Institute of Ocean Sciences, St. Georges, Bermuda

The Sargasso Sea is a dynamic region in the North Atlantic Ocean, delimited by the western boundary current that forms
part of the North Atlantic Gyre, and is often depicted as an oligotrophic environment. In the Sargasso Sea, most of the
primary production occurs between 80 and 120 m, at the deep chlorophyll maximum (DCM). The haptophytes, a cladeof algae that share a common evolutionary ancestor, represent the main group of eukaryotes in the Sargasso Sea, asdetected by total integrated Chl-a biomass. From this group, coccolithophores are arguably the best-known organisms
due to their contribution to global carbon cycles as key calcifying primary producers. Hence, multiple projects aroundthe world have been carried out to study coccolithophore communities from disparate locations, usually based on cruisesof opportunity, such as latitudinal oceanic transects across the Atlantic Ocean close to the Mid-Atlantic Ridge. This hascreated a disproportionate dataset, which is often used to represent the entire ecosystem. On the western side of the North
Atlantic, research on phytoplankton communities has been undertaken at the Bermuda Atlantic Time-series (BATS)
stations by various groups, but not to the level of the taxonomic identiﬁcation of the coccolithophores, which we remedy
in this presentation. Our examinations, as part of a short study focusing on the lower photic zone, of samples collectedfrom Hydrostation S show a high biodiversity not previously reported. We found that the BATS coccolithophorecommunity during the fall of 2020 comprised 206 morphotypes, of which 90 were present at 20 m depth, and 182 in thelower photic zone (DCM and below). Of those, at least 40 morphotypes were completely new to science or undescribed.

INA1877

Separation of coccoliths from sediments: An automatedprotocol for palaeoclimatic investigations
Fabrice Minoletti
Sorbonne Université, Institut des Sciences de la Terre de Paris (UMR 7193 ISTeP), Paris, France; fabrice.minoletti@sorbonne-universite.fr

Michaël Hermoso
Université du Littoral Côte d’Opale, Laboratoire d’Océanologie et de Géosciences (UMR 8187 LOG), Wimereux, France

Camille Godbillot
Previously Sorbonne Université, Institut des Sciences de la Terre de Paris (UMR 7193 ISTeP), Paris, France & now CEREGE (UMR 7330), CNRS,
Aix-Marseille Université, IRD, College de France, INRA, Aix-en-Provence, France

Goulwen le Guevel
Sorbonne Université, Institut des Sciences de la Terre de Paris (UMR 7193 ISTeP), Paris, France

Maxime Tremblin
Previously Sorbonne Université, Institut des Sciences de la Terre de Paris (UMR 7193 ISTeP), Paris, France & now Department of Earth Sciences,
Université de Genève, Genève, Switzerland

Palaeoclimatic reconstructions are commonly based on geochemical data measured on manually isolated planktonic
foraminifera. These tests are often affected by diagenetic overgrowth and recrystallisation (frosty vs glassy tests) that may
obliterate the original palaeoenvironmental signal sought. In addition, uncertainties remain about the calciﬁcation depth
recorded during the vertical migration of foraminifera within the water-column. The analysis of coccoliths has a great
potential to avoid such caveats because they are produced by autotrophic algae in the uppermost water-column and theirintricate ultrastructures limit signiﬁcant overgrowth. However, their tiny dimensions, which prevent manual isolation,
have limited their use in palaeoceanography, although this has motivated considerable efforts in the development ofprotocols allowing their targeted analysis.
By using cascade ﬁltering steps on polycarbonate membranes with well-calibrated pores, coccoliths may be split
into distinct fractions (Minoletti et al., 2009). A large variety of geochemical and morphometric proxies can be applied
to the separated fractions to assess palaeoenvironmental parameters, such as sea-surface temperatures and CO2 levels.
Recent developments allow the protocol to be applied automatically by using various electronic components (water level
detectors, DC motors and pumps) in order to reduce the duration of the process and run multiple samples in parallel.
This protocol has been applied in different sedimentary contexts and time periods, spanning from the Toarcian to the
Pleistocene, and forms the technical underpinning of several other studies presented at INA18.
References

Minoletti, F., Hermoso, M. & Gressier, V. 2009. Separation of sedimentary micron-sized particles for palaeoceanography andcalcareous nannoplankton biogeochemistry. Nature Protocols, 4: 14–24.

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Surface-water variations during the Middle and Late
Pleistocene in the Mozambique Channel based on calcareous
nannofossil assemblages
Haley Mossell
Department of Geology and Geophysics, Texas A&M University, Halbouty Building, 3115 TAMU, 611 Ross St., College Station, TX 77843, USA;
haley.moss@tamu.edu

Denise K. Kulhanek
Institute of Geosciences, Christian-Albrechts-University of Kiel, Ludewig-Meyn-Straße 10–14, 24118, Kiel, Germany

Gary D. Acton, Leah LeVay
International Ocean Discovery Program, Texas A&M University, 1000 Discovery Drive, College Station, TX 77845, USA

Calcareous nannofossils are what remains of calcareous phytoplankton after they die and ﬁnd their way to the ocean
ﬂoor. While these organisms are alive, they record changes in the surface temperature of the ocean. For instance,
Gephyrocapsa oceanica is strongly linked to warm ocean waters, whereas cooler waters are favoured by Gephyrocapsa
muellerae. Calcareous nannofossils can also provide information about the availability of nutrients in surface waters.
For example, Gephyrocapsa spp. (<3 µm) prefer higher nutrient availability. Conversely, Florisphaera profunda, aspecies that lives in the lower photic zone, is only abundant when nutrients are available deep in the water-column,
indicating stratiﬁed waters and decreased nutrients in the upper photic zone due to an absence of upwelling occurring in
the region. Thus, nannofossil assemblages can be used to document how the climate has changed through Earth’s history.
We examined nannofossil assemblages in samples collected from the piston core MD13-3504, obtained by the R/VMarion Dufresne during research cruise MD13 to the Mozambique Channel. The Mozambique Channel is locatedbetween the island of Madagascar and Mozambique in East Africa and serves as a path for warm water from theequatorial Indian Ocean to enter the south-western Indian Ocean via the Agulhas Current. The Agulhas Current
also injects warm, saline water into the South Atlantic Ocean via the Agulhas leakage, thereby inﬂuencing Atlantic
meridional overturning circulation. Calcareous nannofossil biostratigraphy, using the appearance of Emiliania huxleyi
and disappearance of Pseudoemiliania lacunosa, indicated that the sediment core was Middle to Late Pleistocene, withthe oldest sample examined being from >430 ka. Sea-surface temperatures were generally warm through this timeinterval, as the nannofossil assemblages were dominated by warm-water taxa, such as G. oceanica, Rhabdosphaera spp.
and Helicosphaera spp. Cold-water species, such as Coccolithus pelagicus and G. muellerae appeared for brief time
periods throughout the studied interval. Surface-water stratiﬁcation increased through time, especially in the interval
younger than 290 ka, based on high abundances of F. profunda and low N ratio values. These results suggest warmer andmore oligotrophic waters dominated in the region over the last ~200 kyr.

INA1879

Provenance analysis of historic mortars and mortar basedmaterials: A micropalaeontological approach
Joerg Mutterlose, Janina Falkenberg
Institute of Geology, Mineralogy and Geophysics, Ruhr-Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany; joerg.mutterlose@
rub.deUlrich Kaplan
Eichenallee 141, 33332 Gütersloh, Germany

Mortar has been the essential construction agent of buildings for more than 9000 years, with lime being the most widelyused mortar-binder in historic buildings. To produce lime mortars, naturally occurring limestone is heated to >800ºC,
causing a thermal decomposition into quicklime (CaO). Post-Triassic limestones often contain calcareous nannofossils.
These calcitic, single-celled, marine photoautotrophic algae (<30 µm) have been signiﬁcant components of Earth’s
biogeochemical cycle since the Jurassic and have been, as such, well-studied in the ﬁelds of oceanography, marine
biology, micropalaeontology and geology. Here, we focus on the neglected application of these algae in archaeology
and related ﬁelds.
We analysed 28 mortar samples from six archaeologically well-dated medieval churches (800–1510 AD) from the
Münsterland Basin (northern Germany) for their calcareous nannofossil content. Notwithstanding substantial heating,most samples yielded low-diversity assemblages, which provided, in some cases, reliable biostratigraphic ages for the
limestone. In all examples, locally outcropping limestones were used; in one case, the lime was transported over a
distance of 20 km. The medieval builders preferred limestones over marly limestones, even when the latter were exposed
closer to the former building site. In the case of Paderborn Cathedral, different limestone resources were used over the
500 years of construction, suggesting that socioeconomic factors (e.g. land ownership) partly controlled the source areaof the quarried material.
The general lesson from the current study is that calcareous nannofossils are: 1) present in mortar and mortar-basedmaterials (render, including coloured versions) of historic buildings; and 2) a good tool for the provenancing of mortars(even a few nannofossil ﬁndings can sufﬁce).

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Emiliania huxleyi biometry and calcification response
to environmental gradients in the Indian sector of theSouthern Ocean
Shramik Patil, Rahul Mohan
National Centre for Polar and Ocean Research, Goa 403804, India; shramikpatil@gmail.com

Suhas Shetye
National Institute of Oceanography, Goa 403804, India

Vailancy Vaz, Sahina Gazi
National Centre for Polar and Ocean Research, Goa 403804, India

Pallavi Choudhari
Centre for Marine Living Resources and Ecology, Kerala 682508, India

Syed Jafar
National Centre for Polar and Ocean Research, Goa 403804, India

An increase in atmospheric pCO2 and temperature is expected to reduce ocean CO32- concentrations, make oceans warmer and alter ocean circulation patterns. This will also affect the production and biogeographic distribution of marine
calcifying organisms, including coccolithophores. The lowering of oceanic CO32- is expected to interfere with the coccolithophore calciﬁcation process and cause the malformation of coccoliths, whereas changes in oceanic temperaturesand circulation patterns may shift their biogeographical boundaries. In this study, we have investigated the Emiliania
huxleyi coccolith and coccosphere size response to the wide-ranging physicochemical conditions of the Indian sector of
the Southern Ocean between 38ºS and 58ºS during the austral summer of 2010 (January–February). This study is helping
us to understand the response of the E. huxleyi coccolith/coccosphere morphometry and mass changes to the ﬂuctuating temperatures, salinity, CO32-, pCO2 and nutrient values. Our results show that, in the Indian sector of the Southern
Ocean, E. huxleyi coccoliths were larger and the coccospheres smaller in the Subtropical Zone (STZ). By contrast, thecoccolith size was smaller and the coccospheres larger in the Subantarctic Zone (SAZ), due to a decrease in sea-surface
temperatures and sea-surface salinity and an increase in nutrient concentrations. In the Indian sector of the Southern
Ocean, E. huxleyi shows a N–S morphotype shift from the heavily calciﬁed ‘Group A’ (E. huxleyi morphotype A) to theweakly calciﬁed ‘Group B’ (E. huxleyi morphotypes B/C, C) forms. We have demonstrated that, although weakly calciﬁed E. huxleyi morphotypes (morphotypes B/C and C) form less mass than E. huxleyi morphotype A, due to the large
coccospheres and numerous coccoliths per coccosphere, ‘Group B’ coccospheres precipitate a large amount of CaCO3
in the SAZ compared to Group A coccospheres located in the STZ. We have documented the presence of large, overcalciﬁed E. huxleyi coccospheres with large coccoliths in the southernmost cold, high pCO2 and nutrient-rich waters,
which promoted extracellular calcite precipitation. An energy-dispersive spectrometry analysis indicated the presenceof a large amount of Mg in the overcalciﬁed E. huxleyi specimens. We suspect that, with future projected changes in the
carbonate chemistry, the E. huxleyi in colder, nutrient-rich waters may adapt to low-pH, high-pCO2 conditions throughextracellular Ca and Mg mineralisation.

INA1881

Coccolithophore palaeoproductivity in the south-western
Atlantic during the last seven terminations

Guilherme Pedrão, Karen Costa, Mariana Tomazella, Rubens Figueira, Bianca
Kim, Felipe Toledo
University of São Paulo, São Paulo, Brazil; guilherme.pedrao@usp.br

Glacial terminations are periods that stand out throughout the Quaternary due to their association with abrupt increases
in CO2 concentrations and temperature. In this context, a better understanding of how coccolithophores can respondto such changes is essential, since they are a vital part of the carbon cycle. Here, we investigated variations in coccolithophore palaeoproductivity in the south-western Atlantic Ocean during the last seven terminations, analysing thebulk coccolith fraction Sr/Ca ratios (CF Sr/Ca). Additionally, we compared these results with the relative abundances of
species to infer how these organisms and their productivity responded to climatic variations and related oceanographic
processes.
The CF Sr/Ca data showed the highest productivity rates during the glacial terminations. The most dominant groupduring the studied period was Gephyrocapsa spp. However, Florisphaera profunda and small placoliths were also
highly abundant in occasional intervals. Subordinate species (Helicosphaera spp., Coccolithus pelagicus and Calcidiscus leptoporus) were important indicators, appearing in more signiﬁcant relative abundances during periods of high productivity. Comparisons with estimated sea-surface temperatures suggest the presence of the nutrient-rich South Atlantic
central water mass in the lower photic zone, but not reaching the sea surface. This process was associated with variations
in seasonality, caused primarily by changes in Earth’s orbital cycles. We also noticed changes in benthic foraminiferal
assemblages in the same periods as the high coccolithophore productivity. An increase in species that indicate a highorganic-matter contribution to the seaﬂoor suggest a benthopelagic coupling, and that at least part of the productivity
generated at the surface was being exported to the deep ocean, indicating that coccolithophores played a signiﬁcant rolein the regional carbon cycle.

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Late Triassic calcareous nannofossils from Argentina andPeru unravel an early dispersal pathway through Panthalassa
Juan Pablo Pérez Panera
Consejo Nacional de Investigaciones Cientíﬁcas y Técnicas (CONICET) & División Geología, Museo de La Plata, Facultad de Ciencias Naturales y
Museo, Universidad Nacional de Buenos Aires, Pase del Bosque s/n, CP 1900, La Plata, Buenos Aires, Argentina; perezpanera@gmail.com

Calcareous nannofossils ﬁrst appear in the Middle Norian in the Western Tethys, Northern Calcareous Alps, with
the nannolith Prinsiosphaera triassica and small unidentiﬁed coccolith-like rims (Demangel et al., 2020). The
coccolithophores Crucirhabdus minutus and Archaeozygodiscus koessenensis sporadically appeared after the Late Norianin the same area, and P. triassica dispersed to south-eastern Tethys and the eastern Paciﬁc (Bown, 1992; Demangel et al.,2020). By the Early Rhaetian, Crucirhabdus primulus and Eoconusphaera hallstattensis had ﬁrst appeared in westernand south-eastern Tethys, followed by Eoconusphaera zlambachensis (Demangel et al., 2021). In the south-eastern
Paciﬁc, recently investigated Late Triassic successions from the Neuquén Basin, Argentina, and the Pucrará Group,
north-western Perú, have revealed the presence of P. triassica in the Late Norian and Rhaetian and E. zlambachensis
and C. minutus in the Rhaetian (Pérez Panera et al., 2021a, b). These ﬁndings correspond to the second record of thisgroup outside the Tethyan Realm, after the ﬁnding of P. triassica and C. minutus in the Norian and Rhaetian in the
Queen Charlotte Islands, western Canada (Bown, 1992). Tethyan assemblages have higher species richness and younger
records than the eastern Paciﬁc ones, suggesting a Tethyan origin and diversiﬁcation, and a continuous dispersal throughthe Panthalassa to the eastern Paciﬁc. According to oceanic circulation models for the Late Triassic, southern easterly
cool-water currents may have connect south-eastern Tethys with the south-eastern Paciﬁc, dispersing the calcareous
nannoplankton. Once the nannoplankton reached the south-eastern Paciﬁc continental margins, they could disperseto the north, transported by contouritic currents. This hypothesis supposes a permanent connection through the Late
Triassic, and could explain the reduced species richness in the eastern Paciﬁc due to a progressive loss in diversity
across the dispersal route. Western and south-eastern Tethys, which were connected along continental shelves and weresettled at tropical to subtropical latitudes, shared equal species-richness values. A ﬁrst loss in species richness occurredfrom south-eastern Tethys to the south-eastern Paciﬁc (Neuquén Basin and Pucará Group), with the absence of E.
hallstattensis, A. koessenensis and C. primulus (although this species is later recorded in the Early Jurassic). This loss
represented 50% of the species richness and made sense, assuming that this part of the dispersal pathway involved
passive transport across the open ocean and by cool-water currents. From the south-eastern Paciﬁc, nannoplankton had
a relatively easy path to the Northeastern Paciﬁc. Even so, the loss of species richness continued, given the absence ofE. zlambachensis from the Queen Charlotte Island sections (Bown, 1992). Although south-eastern and north-eastern
Paciﬁc basins were probably continuously connected by continental shelves, the strong equatorial westerly oceanic
currents may have acted as an important barrier against dispersion between these areas.
References
Bown, P.R. 1992. Late Triassic–Early Jurassic calcareous nannofossils of the Queen Charlotte Islands, British Columbia. Journal of Micropaleontology,
11(2): 177–188.
Demangel, I., Howe, R., Gardin, S. & Richoz, S. 2021. Eoconusphaera hallstattensis sp. nov. and a review of the Rhaetian genus Eoconusphaera.
Journal of Nannoplankton Research, 39(1): 77–87.
Demangel, I., Kovacs, Z., Richoz, S., Gardin, S., Krystyn, L., Baldermann, A. & Piller, W.E. 2020. Development of early calcareous nannoplankton
in the Northern Calcareous Alps (Austria) in the Late Triassic. Global and Planetary Change, 193: 103254.
Pérez Panera, J.P., Angelozzi, G.N., Riccardi, A.C., Damborenea, S.E. & Manceñido, M.O. 2021a. Triassic calcareous nannofossils from the Arroyo
Malo Formation, Neuquén Basin, Argentina. First record in South America and implications on the early evolution of the group. 12º Congreso dela Asociación Paleontológica Argentina, Buenos Aires: 77.
Pérez Panera, J.P., Calvo Marcilese, L., Cuello, M.J. & Giampaoli, P. 2021b. First record of calcareous nannofossils from Chambará Formation, PucaráGroup, Perú: A new biostratigraphic tool for regional correlation in the Late Triassic? 12º Congreso de la Asociación Paleontológica Argentina,
Buenos Aires: 92.

INA1883

Paleogene calcareous nannofossils from IODP Site U1553:
Biostratigraphic, palaeoecological, and palaeoceanographic
implications
Davide Persico
Dipartimento di Scienze chimiche della vita e della sostenibilità ambientale (SCVSA), Università degli Studi di Parma, Plesso di Scienze della
Terra, Parco Area delle Scienze 157A, 43100 Parma, Italy; davide.persico@unipr.it

Isabella Raffi
Dipartimento di Ingegneria e Geologia (InGeo), Università degli Studi “G. d’Annunzio” di Chieti-Pescara, Campus Universitario, via dei Vestini 31,
66013 Chieti Scalo, Italy

Chiara Fioroni
Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, Via Campi, 103 41125 Modena, Italy

Giuliana Villa
Dipartimento di Scienze chimiche della vita e della sostenibilità ambientale (SCVSA), Università degli Studi di Parma, Plesso di Scienze della
Terra, Parco Area delle Scienze 157A, 43100 Parma, Italy

In January 2020, International Ocean Discovery Program (IODP) Expedition 378 drilled in the South Paciﬁc andrecovered a continuously cored, multiple-holed Paleogene sedimentary section at Site U1553, located in the southern
Campbell Plateau (Thomas et al., 2020). The aim was to replicate the sedimentary record of DSDP Site 277, drilled during
Leg 29 in 1973, known as a reference palaeoceanographic section for the Paleogene (Kennett et al., 1975). From DSDP
Site 277, two classic oxygen isotope records were generated that ﬁrst deﬁned the climatic evolution through the Eocene(Shackleton and Kennett, 1974; Savin, 1977). Improvements in coring technologies and better core–log integration haveresulted in the development of triple-core stratigraphic splices that have resulted in a more complete succession than
the single, partially spot-cored hole of Site 277. Research investigations on Site U1553 by high-resolution sampling are
in progress, and allow the study, in unprecedented detail, all the biostratigraphic events preserved in this high-latitude
sedimentary record (Fioroni et al., 2012; Hollis et al., 2015).
Here, we report on a preliminary study on calcareous nannofossil assemblages in an expanded Upper Eocene to Upper
Oligocene sequence (with sedimentation rates of 19–22 m/Myr). The initial biostratigraphic results have conﬁrmed thevalidity of the biozonation scheme proposed for the Southern Ocean (Fioroni et al., 2012) and suggest that further
reﬁnements of that biostratigraphic framework can be obtained from Site U1553, taking advantage of the rich andgenerally well preserved nannofossil assemblages observed in the studied interval.
The succession of recognised bioevents was compatible with the biozonation scheme proposed by Fioroni et al.
(2012), placing the stratigraphic sequence studied in an interval between the Late Eocene and the Oligocene (from the E.
formosa to C. altus zones). High-resolution biostratigraphic analyses of the lower part of the composite section showed
differences in the stratigraphic distributions of I. recurvus and R. clatrata with respect to what has been observed at other
Southern Ocean locations and reported in the biozonation of Fioroni et al. (2012).
A preliminary palaeoecological analysis was performed at low resolution on Hole U1553E. This suggested thatdifferent groups of taxa, considered representative of cool, temperate, eutrophic or oligotrophic conditions, may provide
proxies for palaeotemperatures and nutrient concentrations, in line with previous studies at high southern-latitude sites(Villa et al., 2014). Further studies in progress at higher resolutions will certainly help in reconstructing changes in theSouth Paciﬁc sea-surface temperature (SST), circulation and productivity associated with the greenhouse–icehousetransition (Eocene/Oligocene transition) and throughout the Early Oligocene interval. Moreover, the rich and wellpreserved assemblages will provide new knowledge about the phylogeny of some species, such as R. clatrata and R.
oamaruensis.

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References
Fioroni, C., Villa, G., Persico, D., Wise, S.W. & Pea, L. 2012. Revised Middle Eocene–Upper Oligocene calcareous nannofossil biozonation for theSouthern Ocean. Revue de Micropaléontologie, 55: 53–70.
Hollis, C.J., Hines, B.R., Littler, K., Villasante-Marcos, V., Kulhanek, D.K., Strong, C.P., Zachos, J.C., Eggins, S.M., Northcote, L. & Phillips, A. 2015.
The Paleocene–Eocene Thermal Maximum at DSDP Site 277, Campbell Plateau, southern Paciﬁc Ocean. Climate of the Past, 11: 1009–1025.
Kennett, J.P., Houtz, R.E., Andrews, P.B., Edwards, A.R., Gostin, V.A., Hajós, M., Hampton, M., Jenkins, D.G., Margolis, S.V., Ovenshine, A.T. &Perch-Nielsen, K. 1975. Introduction and explanatory note. Initial Reports of the DSDP, 29.
Savin, S.M. 1977. The history of the Earth’s surface temperature during the past 100 million years. Annual Review of Earth and Planetary Sciences,
5: 319–355.
Shackleton, N.J. & Kennett, J.P. 1974. Paleotemperature history of the Cenozoic and the initiation of Antarctic glaciation: Oxygen and carbon isotope
analyses in DSDP Sites 277, 279 and 281. Initial Reports of the DSDP, 29: 743–755.
Thomas, D.J., Röhl, U., Childress, L.B. and the Expedition 378 Scientists 2020. Expedition 378 preliminary report: South Paciﬁc Paleogene Climate.
International Ocean Discovery Program.
Villa, G., Fioroni, C., Persico, D., Roberts, A.P. & Florindo, F. 2014. Middle Eocene to Late Oligocene Antarctic glaciation/deglaciation and Southern
Ocean productivity. Paleoceanography, 29: 223– 237.

INA1885

New estimation of Late Paleocene calcareous
nannoplankton ﬂuxes from ODP Site 1209 (North Pacific)
Nicolas Pige, Guillaume Suan
Université Lyon 1, ENSL, UJM, CNRS, LGL-TPE, F-69622, Villeurbanne, France; nicolas.pige@univ-lyon1.fr

Pierre-Henri Blard
CRPG, Université de Lorraine, CNRS, UMR7358, Nancy, France

Emanuela Mattioli
Université Lyon 1, ENSL, UJM, CNRS, LGL-TPE, F-69622, Villeurbanne, France

The Early Paleogene was punctuated by several greenhouse-gas-driven hyperthermal events, the best known being
the Paleocene–Eocene Thermal Maximum (PETM, 56 Ma). Planktonic organisms have been severely impacted by theenvironmental changes induced by abrupt events like these. Calcareous nannoplankton produce calcite shields using
the dissolved carbon in oceanic surface waters, and these constitute a major component of deep-sea sediments. It isthus essential to produce highly resolved records of their production and burial across hyperthermals in order to better
constrain their role in mitigating or amplifying ancient carbon-cycle perturbations.
Here, we present a quantitative assessment of the abundances of calcareous nannofossils and their fragments across a
1.2-Myr interval prior to the PETM at ODP Site 1209 (Paciﬁc Ocean). The quantiﬁcation of nannofossil fragment sizes
and shapes allowed us to recalculate the nannofossil absolute abundances. We have developed a new age-model basedon extraterrestrial 3He to reconstruct ﬂuxes of the exported calcite particles throughout the water-column. In parallel,dissolution was reconstructed thanks to planktonic foraminifera fragmentation and the sediment coarse fraction so as todisentangle the respective effects of production and dissolution on the nannofossil record.
Our main results challenge the widely accepted model previously developed for hyperthermal events, according
to which CaCO3 accumulation is mainly controlled by dissolution. Our results suggest that other parameters, such astemperature, water stratiﬁcation and nutrient availability, exerted a major inﬂuence on carbonate production, export andaccumulation for most of the Late Paleocene hyperthermal events.

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Morphometric changes in two Late Cretaceous calcareous
nannofossil lineages support diversification fueled by longterm cooling
Mohammad J. Razmjooei
Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen C, Denmark& Department of Geological Sciences, Stockholm University, 106 91 Stockholm, Sweden; mj.razmjooei@gmail.com

Nicolas Thibault
Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen C, Denmark

Morphometric changes in two calcareous nannofossil species––Cribrosphaerella ehrenbergii and Microrhabdulus
undosus––were investigated in the Campanian–Maastrichtian. The results revealed a common episode of size increaseat ~76 Ma, with a sudden shift in the size of C. ehrenbergii towards larger specimens and with the emergence ofa larger, newly described species of Microrhabdulus––sp. nov. 1. An even larger species emerged at ~69 Ma in theMicrorhabdulus lineage––Microrhabdulus sp. nov. 2. The timing of these size changes and origination events matches
global changes in nannoplankton diversity and/or in the diversity of other planktonic organisms and cephalopods. A
comparison with long-term global climate change supports these new biometric and evolutionary events representing
an excellent illustration of the Late Cretaceous global rise in nannoplankton diversity and size, being associated withclimatic cooling and/or climatic instability.

INA1887

Mid-Pleistocene to Holocene calcareous nannofossil
taxonomy and biochronology of the central Arctic Ocean
Mohammad J. Razmjooei, Matt O’Regan
Department of Geological Sciences, Stockholm University, Stockholm SE-106 91, Sweden; mj.razmjooei@gmail.com

Jorijntje Henderiks
Department of Earth Sciences, Uppsala University, Uppsala SE-752 36, Sweden

Karl-Heinz Baumann
Geosciences, University of Bremen, PO Box 330440, 28334 Bremen, Germany

A half-century of research (since the 1970s) has indicated that accurate dating of the sediments in the Arctic Ocean
is not straightforward due to some puzzling magnetic polarity patterns, the lack or scarcity of microfossils, and thediscontinuous oxygen isotope records from Arctic marine sediments. Recently, two important biohorizons of calcareous
nannofossils, including the ﬁrst occurrence of Emiliania huxleyi (291 ka: Rafﬁ et al., 2006) and the last occurrence ofPseudoemiliania lacunosa (436 ka: Rafﬁ et al., 1977) were reported for the ﬁrst time from the central Arctic (LRG123PC) (O’Regan et al., 2020). In order to study the taxonomic composition and abundance of the calcareous nannofossil
taxa and expand on the results provided by O’Regan et al. (2020), a high-resolution stratigraphic analysis of Upper
Quaternary sediments was undertaken on three cores from the Lomonosov Ridge (LRG12-7PC, LRG12-9PC and
AO16-5-PC1) and one from the Makarov Basin (AO16-8GC) in the central part of the Arctic Ocean. Although ourstudies conﬁrm the presence of the two bioevents across the central Arctic, the extremely low abundances and variable
preservation can make it very difﬁcult to conﬁdently resolve their stratigraphic positions. Through detailed sampling andcross-veriﬁcation, using transmitting light and scanning electron microscope imaging, a new stratigraphic frameworkthat supports the key bioevents is emerging. This may signifcantly change the geochronological framework for central
Arctic Ocean sediments, with the implication that what were previously identiﬁed as substages (interstadials) in Marine
Isotope Stage 5 were actually separate interglacials. The presence and absence patterns of the nannofossil markers inthe studied cores allowed the standard NN19, NN20 and NN21 nannofossil zones of Martini (1971) to be applied, thus
placing the upper 2–3 m of the cores in the Mid-Pleistocene to Holocene.
References
Martini, E. 1971. Standard Tertiary and Quaternary calcareous nannoplankton zonation. In: A. Farinacci (Ed.). Proceedings of the II Planktonic
Conference, Roma, 1970. Edizioni Tecnoscienza, Roma: 739–785.
O’Regan, M., Backman, J., Fornaciari, E., Jakobsson, M. & West, G. 2020. Calcareous nannofossils anchor chronologies for Arctic Ocean sedimentsback to 500 ka. Geology, 48(11): 1115–1119.
Rafﬁ, I., Backman, J., Fornaciari, E., Pälike, H., Rio, D., Lourens, L. & Hilgen, F. 2006. A review of calcareous nannofossil astrobiochronology
encompassing the past 25 million years. Quaternary Science Reviews, 25(23–24): 3113–3137.

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Perturbing coccolithophores: The past and future of Earth’s
stabilisers
Rosalind E. M. Rickaby
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK; rosalind.rickaby@earth.ox.ac.uk

Coccolithophores are single-celled, photosynthesising algae that precipitate a multitude of intricate calcium carbonate
liths inside their cells before expelling them to form external spherical armour. Although microscopic in stature,
coccolithophores have exerted a gigantic inﬂuence on Earth’s carbon cycle since their emergence in the Triassic.
Massive accumulations of calcium carbonate coccoliths (an estimated ﬂux of ~6 x 1025 liths/year) contribute to theexport of organic matter from the mixed layer, and ultimately form sediments on the deep seaﬂoor, a dominant sinkof carbon from the atmosphere over geological timescales, playing a role in Earth’s thermostat and acting as a buffer
for seawater chemistry. Through this carbon sink, the coccolithophores have exerted an inﬂuence on the ocean andatmosphere, but similarly, this changing carbon cycle has driven genetic and physiological innovation and adaptation
within the coccolithophores. In this talk, I will explore, using novel bio(geo)chemical tools, how coccolithophores andthe environment are linked in an inescapable feedback in the geological past, and how looking to the past may help topredict their future destiny in a rising-carbon world.

INA1889

Calcareous nannoplankton from the uppermost Triassic of
the Southern Alps, Slovenia
Matic Riﬂ, Katarína Holcová
Institute of Geology and Palaeontology, Albertov 6, Prague 2, 128 43, Czech Republic; riﬂ.matic@gmail.com

In Slovenia, Upper Triassic limestone outcrops represent one of the most widespread lithologies. Most of these are
currently exposed in the mountain faces of the Southern Alps and the steep hills of the External Dinarides. The Upper
Triassic carbonate successions were deposited on the passive western margin of Pangaea facing the Tethys Ocean.
These sediments were tectonically uplifted through convergence and subduction processes, now allowing us to get an
insight into the formerly predominantly marine environments of the region. Norian and Rhaetian beds in Slovenia lay
conformably on Carnian rocks and show a continuous upwards transition into the different settings of the Early Jurassic.
The aim of this research was a preliminary study of the uppermost Triassic calcareous nannoplankton.
During the Late Triassic, the formation of the Central Atlantic Magmatic Province propagated changes governed byrelatively short-term pH oscillations, which reshufﬂed the balance of the global oceanic biogeochemical cycles. Despite
the number of scientiﬁc publications focusing on Late Triassic nannofossils, little is known about the nannoplankton
assemblages during their ﬁrst mass extinction close to the Triassic/Jurassic boundary. The Upper Norian to Rhaetian
Slatnik Formation, located in the Kobla Nappe Complex, is seen as a continuous basinal development from Late Triassic
to Early Jurassic facies. Samples were taken from the uppermost Triassic part of the Povdnar section, which is composedof thinly bedded to platy marlstones and marly limestones, which have been interpreted as hemipelagic or partly distal
turbidites. The extraction of coccoliths from these carbonate rocks is challenging due to the diagenetic overprint.
The samples were crushed in a mortar and dry-sieved over a 0.02-mm sieve. The crushed sediment was frozen andthen boiled in water with an added dispersion agent. Ultimately, the calcareous nannoplankton were studied on smear
slides over 200 ﬁelds of view. Using this approach, we were able to conﬁrm that calcareous nannoplankton occurred
more frequently in the marlstone than in the marly limestones. The assemblages identiﬁed were mostly represented byrecrystallised nannoliths belonging to Prinsiosphaera triassica and, more rarely, Eoconusphaera zlambachensis. Future
research will focus on further steps in wet sieving and sample enrichment. We intend to sieve the sample using a 63µm mesh and dilute the suspension to a uniform volume. For the sample enrichment, we have assembled a multistage
apparatus that will enable the repeated wet vacuum-powered acoustic microﬁltration of particles smaller than 1 µm,
which end up in a collection vessel. The calcareous nannoplankton will be further studied using a scanning electron
microscope. Finally, the nannofossil diversity, abundance and facies dependence will be compared to those from otherupper Norian–Rhaetian sections in Slovenia and the Western Carpathians in Slovakia.

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Role of coccolithophore ﬂoristics on alkenone-derived
temperatures in the subantarctic Southern Ocean
Andrés S. Rigual-Hernández, Francisco J. Sierro, José Abel FloresÁrea de Paleontología, Departamento de Geología, Universidad de Salamanca, 37008 Salamanca, Spain; arigual@usal.es

Tom W. Trull
CSIRO Oceans and Atmosphere, Hobart, Tasmania 7001, Australia & Institute for Marine and Antarctic Studies, University of Tasmania, Private
Bag 129, Hobart, Tasmania 7001, Australia & Antarctic Climate and Ecosystems Cooperative Research Centre and Australian Antarctic Program
Partnership, University of Tasmania, Hobart, Tasmania 7001, Australia

Teresa Rodrigues
Portuguese Institute for Sea and Atmosphere (IPMA), Divisão de Geologia Marinha, Rua Alfredo Magalhães Ramalho 6, Lisboa, Portugal &CCMAR, Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal

Belén Martrat
Department of Environmental Chemistry, IDAEA-CSIC, 08034 Barcelona, Spain

Elizabeth Sikes
Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA

Scott D. Nodder
National Institute of Water and Atmospheric Research, Wellington 6021, New Zealand

Ruth S. Eriksen
CSIRO Oceans and Atmosphere, Hobart, Tasmania 7001, Australia & Institute for Marine and Antarctic Studies, University of Tasmania, Private
Bag 129, Hobart, Tasmania 7001, Australia

Diana Davies
CSIRO Oceans and Atmosphere, Hobart, Tasmania 7001, Australia & Antarctic Climate and Ecosystems Cooperative Research Centre andAustralian Antarctic Program Partnership, University of Tasmania, Hobart, Tasmania 7001, Australia

Natalia Bravo
Department of Environmental Chemistry, IDAEA-CSIC, 08034 Barcelona, Spain

José M. Sánchez-Santos
Departamento de Estadística, Universidad de Salamanca, 37008 Salamanca, Spain

Fátima Abrantes
Portuguese Institute for Sea and Atmosphere (IPMA), Divisão de Geologia Marinha, Rua Alfredo Magalhães Ramalho 6, Lisboa, Portugal &CCMAR, Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal

Alkenones are a class of unsaturated long-chain methyl and ethyl ketones with a variable degree of unsaturation that
represent one of the most robust proxies for the reconstruction of past sea-surface temperatures (SSTs). Globally, thealkenone unsaturation index has been shown to change linearly with temperature. However, discrepancies between
measured and alkenone-derived temperatures have been documented in subpolar regions of both hemispheres. In order
to assess the inﬂuence of biotic and abiotic factors in alkenone production and preservation in the subantarctic Southern
Ocean, alkenone ﬂuxes were measured in three vertically moored sediment traps (at 1000, 2000 and 3800 m depth)
deployed during one year (from August 2011 to July 2012) at the Southern Ocean Time Series observatory (SOTS) at
46º56’S, 142º15’E.
Overall, alkenone-based reconstructions of water temperatures generally mirror the seasonal variations of temperature
at the surface. However, some important discrepancies (~10ºC deviations) were identiﬁed at the onset of the record (inAugust and September, i.e. austral winter) and attributed to either low light stress or selective degradation of the moreunsaturated alkenones due to prolonged residence time in the water-column. Moreover, the alkenone imprint in the
deepest sediment trap suggested a systematic positive offset of about 3ºC with respect the 1000 and 2000-m traps, which
was attributed to pronounced selective degradation of the more unsaturated alkenones in the lower half of the water-INA1891

column and/or input of allochthonous alkenones transported by a deep eastern boundary current. Notably, we identiﬁed
a strong and signiﬁcant correlation between the seasonal variations of Emiliania huxleyi ecotypes and temperaturedeviations between the alkenone-derived temperatures and in-situ SSTs. Our results suggest that E. huxleyi var. aurorae,
endemic to the Southern Ocean, might produce a higher proportion of C37:3 relative to C37:2 compared to its warmwater counterparts. Thus, it seems likely that the shift in the dominance of E. huxleyi south of the Subantarctic Front
could be at least partially responsible for the less accurate alkenone-based SST reconstructions in the Southern Ocean
using global calibrations.

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Environmental factors inﬂuencing calcareous nannofossil
distribution over the past 96,000 years from the Panama
Basin, eastern equatorial PacificJohn Sarao
Texas A&M University, College Station, TX, USA; john.sarao@tamu.edu

Denise K. Kulhanek
Christian-Albrechts-University of Kiel, Kiel, Germany

Fully and accurately reconstructing changes in productivity and carbon export is critical to determining the efﬁciencyof the biological pump and its role in the global carbon cycle through time, particularly in modern CO2 source regions
like the eastern equatorial Paciﬁc (EEP). Sediment from the Panama Basin (Site MV1014-02-17JC) was used to makesmear-slides by the drop method for the identiﬁcation of calcareous nannofossils through light-microscopy. This
study presents a new, high-resolution record of calcareous nannofossil assemblage changes, together with previously
published diatom assemblage data, and geochemical proxy data, including alkenone-derived sea-surface temperatures(SSTs), 230Th-derived 232Th wind-blown dust ﬂux, 230Th-derived xBa, authigenic uranium, 234U/238U and opal ﬂux, fromthe Panama Basin to assess environmental controls on the phytoplankton community.
The assemblages were well preserved and abundant throughout the 96-kyr record derived from this region. The
assemblages were dominated by Gephyrocapsa oceanica and Florisphaera profunda, with an additional 14 species
being present throughout the studied interval. Principle coordinate analysis (PCO) was used to assess variations in
species abundances among the samples. Each PCO was used as the response variable in a multiple linear regression,
with all environmental factors as predictor variables in order to determine which environmental factors best represented
the changes observed in the ﬂoral composition. The phytoplankton community structure was driven by changing
patterns of nutrient availability (most notably the Si:Fe ratio), which, in turn, was caused by variability in the positionof the Intertropical Convergence Zone (ITCZ) and associated changes in biogeochemical cycling and circulation in
the Southern Ocean. Silica-rich waters brought to the surface from the equatorial undercurrent favoured a diatomdominated community, whereas, when wind-blown dust brought an excess of iron in the absence of bioavailable silica,
the calcareous nannoplankton thrived. Ultimately, this study aims to disentangle the effects of nutrient delivery regimes
along an eastern boundary upwelling system and their controls on the structure of the phytoplankton community.

INA1893

The effect of temperature on the photosynthetic
underpinnings of coccolithophore calcification
Krisztina Sárközi, Rosalind Rickaby
Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK; krisztina.sarkozi@earth.ox.ac.uk

Coccolithophores, like many phytoplankton species, evolved distinct strategies to ﬁne-tune their metabolism to theenvironment, likely by involving the differential allocation of resources between photosynthesis, growth and calciﬁcation
via efﬁciencies and trade-offs between each pathway, and yet there is little mechanistic understanding of how energy andcarbon ﬂow between photosynthesis and calciﬁcation in coccolithophores, and how this dynamic coupling is affected byresource limitation and environmental stress.
We aim to determine how calciﬁcation rate is affected by different strategies of resource allocation under control
conditions and environmental stress by measuring calciﬁcation and photosynthetic rates from alkalinity drift, PIC/POC
and O2-electrode, complemented with SEM observations of size and morphology.
Here, we report some preliminary results on how geographically different isolates of the cosmopolitan bloom-forming
Gephyrocapsa (formerly Emiliania) huxleyi morphotypes, productivity and calciﬁcation change their physiology inresponse to temperature and explore the implications for biogeochemical cycles.

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Late Holocene ecological trends in the Levant Basin fromfossil phytoplankton assemblages
Jakob Schneider, Denise K. Kulhanek
Institute of Geosciences, University of Kiel, Ludewig-Meyn-Straße 10-14, 24118 Kiel, Germany; stu226419@mail.uni-kiel.de

Or M. Bialik
Dr. Moses Strauss Department of Marine Geosciences, The Leon H. Charney School of Marine Sciences, University of Haifa, Carmel 31905, Israel

Guy Sisma-VenturaIsrael Oceanographic and Limnological Research (IOLR), Haifa 3108000, Israel

The Levant Basin in the eastern Mediterranean Sea is largely inﬂuenced by discharge from the Nile River, controllingthe input of freshwater, sedimentary particles and nutrients. Since the 1960s, construction of the Aswan High Dam has
resulted in a signiﬁcant alteration in the aforementioned parameters in the Levant Basin and eastern Mediterranean, in
general. Coccolithophores are suitable organisms for studying ecological ﬂuctuations, as they are highly abundant in theplankton and well preserved in the sediment. Their general signiﬁcance is underlined by their role in primary production
and carbon ﬁxation via calciﬁcation.
To further our understanding of ecosystem variability in this region, we looked at nannofossil assemblages fromthree sites covering the past ~1000 years. The site locations spanned a transect across the continental shelf (Site HS120),rise (Site HO4) and deep basin (Site HO6), and were collected during a cruise of the R/V Bat-Galim with a box-corer(Ocean-Model BX-650). Each core was sectioned into half-centimetre slices immediately after collection and frozen.
We prepared the samples using the drop technique to allow for the calculation of absolute nannofossil abundances.
Census counts for each sample were conducted using cross-polarised and plane transmitted light using a Leica CTR6000
microscope to look at species diversity and abundance. Our initial results show that the nannofossil abundance wassigniﬁcantly higher in the continental rise and deep basin sites relative to the continental shelf site. The coccolithophore
assemblages were dominated by the cosmopolitan taxon Emiliania huxleyi. Less abundant taxa included the genera
Gephyrocapsa, Syracosphaera and Helicosphaera, along with species such as Coccolithus pelagicus, Calcidiscus
leptoporus, Florisphaera profunda, Calciosolenia brasiliensis, Rhabdosphaera clavigera and Braarudosphaera
bigelowii. Diatoms and calcareous dinoﬂagellates (Thoracosphaera sp.) were also present in varying abundances. This
study will elucidate changes in phytoplankton communities in recent history––a time period during which changes inhuman land usage likely had an inﬂuence on the delivery of nutrients into the Mediterranean Sea.

INA1895

Calcareous nannofossil assemblages in sediment cores fromthe northern Red Sea: First results and palaeoecologicalreconstructions
Bhakti Shah
Leibniz Centre for Tropical Marine Research (ZMT), 28359 Bremen, Germany & Centre for Marine Environmental Sciences (MARUM), 28359
Bremen, Germany & University of Bremen, Department of Geosciences, 28359 Bremen, Germany; bhakti.shah@leibniz-zmt.de

Karl-Heinz Baumann
University of Bremen, Department of Geosciences, 28359 Bremen, Germany

Alexander Petrovic
ANPERC, King Abdullah University of Science and Technology (KAUST), ANPERC, 23955 Thuwal, Saudi Arabia & RSRC, King Abdullah
University of Science and Technology (KAUST), ANPERC, 23955 Thuwal, Saudi Arabia

Hildegard Westphal
Leibniz Centre for Tropical Marine Research (ZMT), 28359 Bremen, Germany & University of Bremen, Department of Geosciences, 28359
Bremen, Germany & RSRC, King Abdullah University of Science and Technology (KAUST), ANPERC, 23955 Thuwal, Saudi Arabia

The Red Sea is a desert-surrounded ocean basin with a shallow and narrow seaway to the Indian Ocean. Warm andnormal saline waters enter the Red Sea from the Gulf of Aden, move northwards along the longitudinal axis of thebasin, and become cooler, saltier and oligotrophic. However, the environment suffered extreme oceanographic changes
during the last glacial–interglacial cycle. The water exchange with the Gulf of Aden was even more restricted during thelast glacial, such that the salinity of the Red Sea waters increased considerably, with dramatic effects on its biologicalinterior.
In comparison to other plankton, little is known about the calcareous nannofossils of the Red Sea. Therefore, aqualitative and quantitative study of the calcareous nannofossil assemblages was performed on two sediment coresobtained close to the Al Wajh Platform in the northern Red Sea near the coast of Saudi Arabia. The two 300-cm longcores were sampled at 5–15-cm intervals and prepared for SEM investigations using a combined dilution/ﬁltering
technique. The total calcareous nannofossil numbers range from >10,000 × 106 coccoliths/g in the Holocene (above thetwo sapropels RS1a and RS1b) to numbers of around 4000 × 106 coccoliths/g in the Late Glacial. Abundance variations
occurred across the diverse communities, with up to 35 species and species groups being identiﬁed. This suggests
changes in ecological conditions in the Red Sea, with the higher primary productivity estimates from the Glacialcompared to the Holocene being derived from abundances of the deep-living Florisphaera profunda. Furthermore,signiﬁcantly increased proportions of holococcolithophores in the glacial section indicated good preservation in thisphase, while individual glacial samples were also inﬂuenced by carbonate overgrowth. The observed variations will be
discussed in detail in our poster.

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Improving characterisation of the tight Lower
Cretaceous marly chalk reservoir, central North Sea: A
nannofossil biostratigraphic, sequence stratigraphic andsedimentological approach
Emma Sheldon
Department of Geo-energy and Storage, Geological Survey of Denmark & Greenland (GEUS), Øster Voldgade 10, DK-1350, Copenhagen K,
Denmark; es@geus.dk

Jon Ineson
Department of Geophysics and Sedimentary Basins, Geological Survey of Denmark & Greenland (GEUS), Øster Voldgade 10, DK-1350,
Copenhagen K, Denmark

Kresten Anderskouv
Department of Geosciences and Natural Resource Management, Geology Section, University of Copenhagen, Øster Voldgade 10, DK-1350,
Copenhagen K, Denmark

Lower Cretaceous reservoir-grade chalks and marly chalks have been a secondary target for hydrocarbon explorationand production in Denmark for decades. However, the urgent focus on climate change and the recent end to hydrocarbon
exploration in Denmark has shifted the industry’s attention towards ﬁeld development.
Development of the Valdemar–Boje–Adda area in the Danish sector of the North Sea has required an up-to-dateunderstanding of the architecture of the low-permeability Lower Cretaceous hydrocarbon reservoir. We have carried out
an extensive nannofossil-biostratigraphic, well-log and sedimentological investigation on selected wells from the area.
Industrial biostratigraphic interpretation usually relies on conﬁdential, ﬁeld-speciﬁc, oil-company/consultancy-company
zonation schemes. However, we have applied the published boreal nannofossil zonation schemes––the BC zones ofBown et al. (1998) and the LK zones of Jeremiah (2001)––to the Upper Hauterivian to Barremian Tuxen Formation(BC7–BC16, LK26–LK15) and the Upper Barremian to Lower Aptian Sola Formation (BC16–BC21, LK15–LK12),
which, coupled with new log interpretations and sedimentological logging, have provided a new stratigraphic model forthe area.
The improved stratigraphic framework has increased our understanding of the structural history and sedimentarydevelopment of the area, and has been implemented in reappraisal of the Adda Field. Current studies are focused on
extending this framework to assist further development of the Lower Cretaceous chalks in the Tyra Field to the southeast.
References
Bown, P., Rutledge, D.C., Crux, J.A. & Gallagher, L.T. 1998. Lower Cretaceous. In: P.R. Bown (Ed.). Calcareous nannofossil biostratigraphy. British
Micropalaeontological Society Series. Chapman & Hall/Kluwer Academic: 86–131.
Jeremiah, J. 2001. A Lower Cretaceous nannofossil zonation for the North Sea Basin. Journal of Micropalaeontology, 20: 45–80.

INA1897

Poorly recognised diversity in PIC:POC ratios underpins therole of coccolithophores in the marine carbon cycle
Rosie M. Sheward, Jens O. Herrle
Institute for Geosciences, Goethe-University Frankfurt, Frankfurt am Main, Germany; sheward@em.uni-frankfurt.deAlex J. Poulton
The Lyell Centre for Earth and Marine Sciences, Heriot-Watt University, Edinburgh, Scotland

Throughout their evolutionary history, coccolithophores have shown a spectacular array of diversity in coccolithmorphology, coccosphere architectures and cell size that leads to speciﬁc cellular particulate inorganic carbon (PIC,
calcite) and particulate organic carbon (POC, biomass) characteristics for each species. As biogenic calcite production isa source of CO2 and biomass production is a sink for CO2, there has been extensive investigation into the physiologicaland environmental inﬂuences on the PIC:POC ratio and the development of its use as a major biogeochemical trait
for this plankton group. However, because much of our knowledge of coccolithophore PIC:POC ratios stems fromlaboratory experiments on a limited selection of species in culture (i.e. Emiliania huxleyi) and from bulk analysis of ﬁeld
population samples that integrate the PIC and POC of all species present in the assemblage, the diversity of PIC:POC
ratios across coccolithophore species remains poorly quantiﬁed. This limits our ability to identify which species,
taxonomic or functional groups contribute more (or less) signiﬁcantly to community calcite and biomass production, andtherefore the biogeochemical and ecological consequences of species extinctions, range shifts or changes in productivity
due to climate or biotic pressures.
Here, we present recent insights into the PIC and POC diversity of extant coccolithophores and fossil calcareous
nannoplankton by quantifying the morphology of thousands of individual coccospheres from laboratory cultures,ﬁltered surface seawater samples and well-preserved marine sediments. Across individual cells, the PIC:POC ratios
showed a very broad range, from ~20:1 (e.g. heavily calciﬁed cells of Braarudosphaera) to ~1:20 (e.g. lightly calciﬁed
cells of Kilwalithus), although the majority of individual cells typically lay between a PIC:POC ratio of 2:1 and 1:2.
Taxa that may appear to be ‘heavily calciﬁed’ (e.g. Umbilicosphaera) can have a lower cellular PIC:POC ratio than
expected if they are associated with larger cells (and therefore more POC) and vice versa. The intra-species range in
PIC:POC ratios can also be substantial because this is a function of the variability in coccolith size and morphology,
the number of coccoliths per cell, and cell size. All these parameters have been shown to be inﬂuenced at the cellularlevel by environmental factors and at the population level by the mixing of ecotypes or morphotypes with different
morphological characteristics and physiological states. Overlapping PIC:POC ratio ranges for many species indicate thepotential for some degree of ‘functional redundancy’ in coccolithophore communities, providing that the ecophysiologyof replacement species does not differ substantially. The remarkable diversity in PIC:POC ratios across coccolithophores
past and present strongly suggests that a ‘one-size-ﬁts-all’ approach to coccolithophore PIC:POC ratios is not sufﬁcient
to capture the biogeochemical and ecological consequences of changes in community structure, species productivity orbiogeography.

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Correlation of the calcareous nannofossil biostratigraphiesof the Cenomanian–Turonian Poigny core and Quero section
Michela Simonato
Dipartimento di Geoscienze, Università degli Studi di Padova, Italy; michela.simonato.1@phd.unipd.it

Silvia Gardin
Center for Research on Palaeobiodiversity and Palaeoenvironments, Sorbonne University, Place Jussieu 4, 75252 Paris, France

Valeria Luciani
Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, Italy

Luca Giusberti, Eliana Fornaciari
Dipartimento di Geoscienze, Università degli Studi di Padova, Italy

The Late Cenomanian–Turonian interval was characterised by global changes in the carbon cycle, as identiﬁed bypeaks in stable carbon isotope excursions, associated with climatic variations. Speciﬁcally, the Late Cenomanian records
a warming trend, culminating with Oceanic Anoxic Event 2 (OAE2). However, during the Turonian, frequent coolingphases occurred that ended with a Late Turonian Cool Phase. The palaeoenvironmental variations related to climatechange inﬂuenced the primary producers (e.g. calcareous nannoplankton assemblages), leading to biotic turnover. A
sound biostratigraphic framework is therefore crucial for understanding the tempo and mode of these biotic changes
and the accurate timing of these climatic variations. Calcareous nannofossil assemblages are a useful tool for such
purposes, although some species exhibited diachroneity and/or taxonomic ambiguity (e.g. Eiffellithus eximius) during
the Cenomanian–Turonian interval.
We present new data on the calcareous nannofossil biostratigraphy of the Quero section (Belluno Basin, northeastern Italy) and Poigny core (Paris Basin, France) with the purpose of comparing a southern Boreal core (Poigny)with a north-western Tethyan section (Quero) and assessing the synchroneity/diachroneity of the calcareous nannofossil
biohorizons observed. We have highlight several useful biohorizons and peculiar evolutionary lineages, such as the E.
turriseiffelii to E. eximius evolutionary trend. In addition, we compared the calcareous nannofossil data with those ofplanktonic foraminifera and stable isotopes (Le Callonnec et al., 2021) in order to obtain more accurate information
regarding how the climatic changes inﬂuenced the biotic variations in abundance of selected species, the extinctions andevolutionary radiations. Finally, we correlate our data with those of other reference sections.
References
Le Callonnec, L., Briard, J., Boulila, S., Galbrun, B. 2021. Late Cenomanian–Turonian isotopic stratigraphy in the chalk of the Paris Basin (France):
A reference section between the Tethyan and Boreal realms. BSGF–Earth Sciences Bulletin, 192(1): 1–14.

INA1899

Coccolithophore assemblages from the central Adriatic Sea
Sanda Skejić, Jasna Arapov, Ana Bakrač, Mia Bužančić, Živana
Ninčević GladanInstitute of Oceanography and Fisheries, Šetalište I. Meštrovića 63, 21000 Split, Croatia; sanda@izor.hr

The coccolithophore community was studied in monthly plankton samples from the open waters of the central
Adriatic Sea. The samples were collected along vertical proﬁles up to 100 m deep in 2018. The average contribution of
coccolithophores to the phytoplankton community was 26%. Higher proportions (more than 50%) were recorded in thesurface layers in August, and contributions reached up to 71% in November and December. The average abundance of
coccolithophores throughout the study period was 8.9 x 103 cells l-1, with maximum values of up to 2.6 x 104 cells l-1 in
May, when the highest number of coccolithophore morphotypes was also recorded. The same month was characterisedby the highest HOLP index, indicating the highest number of holococcolith forms.
As for the vertical distribution, the abundance of coccolithophores was highest at 10 m depth and decreased towards
100 m depth. Spearman’s rank correlation showed a positive correlation between Chl-a and diatoms (R = 0.522, p <0.005). Emiliania huxleyi dominated the coccolithophore assemblage in the Adriatic Sea and was also predominant
at all investigated depths, especially from November to March, which is consistent with previous studies. Emiliania
huxleyi accounted for up to 72% of the coccolithophore community during this period. Although the abundance of E.
huxleyi was lower in summer, as was its proportion of the community in the surface layers (only 3%), the proportion of
E. huxleyi increased to as much as 70% in the deeper layers below 50 m depth. In this study, E. huxleyi morphotype A
dominated, but several cells of E. huxleyi type O were also detected. The O morphotype was observed for the ﬁrst timein the Adriatic Sea.

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Did the 33.4 Ma Eastern Rhodope supereruptions contributeto Early Oligocene cooling? Calcareous nannofossil datafrom the St. Sozon section, Limnos
Kristalina Stoykova, Peter Marchev, Raya Raycheva, Rositsa Ivanova,
Georgi Granchovski
Geological Institute, Bulgarian Academy of Sciences, 24 Acad. G. Bonchev Str., BG-1113 Soﬁa, Bulgaria; stoykova@geology.bas.bg, pmarchev@
geology.bas.bg, raya@geology.bas.bg, rossiv@geology.bas.bg, georgi2801@geology.bas.bg

The purpose of the present study was to estimate the impacts of two closely spaced Eastern Rhodope Duzhdovnitsa
supereruptions around the Eocene/Oligocene boundary (EOB) on the marine plankton and climate conditions. To
accomplish these objectives, we studied calcareous nannoplankton assemblages from the St. Sozon section (Fisini–Sardesunit) on Limnos Island, Greece. The section is part of a continuous, >1000-m-thick sedimentary succession (deep-water
turbidites) encompassing the EOB, including two tuff beds. The latter have been precisely dated at 33.38±0.37 Ma and33.31±0.61 Ma, thus providing numerical age constraints for our detailed nannofossil study. The exposures were locatedat St. Sozon Cape (39º48”24.1’N, 25º21”48.5’E), currently situated ~200 km south of the Borovitsa Supervolcano,which is the supposed source of the eruption. The two tuff beds––lower (6.5–7-m thick) and upper (~3.5-m thick)––
were separated by 7 m of sediments. The U–Pb zircon ages for the lower bed (33.38±0.37 Ma and 33.31±0.61 Ma) wereslightly younger than the EOB (33.9 Ma), but very close to the globally recognised Oligocene Oi-1 cooling event.
The total number of nannofossil samples examined was 78. The average sampling resolution was ~5 m, increasing
to 0.2–0.3 m around the tuff layers. For each sample, nannofossils were taxonomically and quantitatively estimatedby logging at least 300 ﬁelds of view on the smear slide. Our biostratigraphic results show that the CNE20, CNE21,
CNO1 and CNO2 nannofossil zones of Agnini et al. (2014) were present. The EOB was identiﬁed by the base common
occurrence of Clausicoccus subdistichus, at 4 m below the base of the ﬁrst tuff bed.
The quantitative analysis of the calcareous nannofossils showed clear differences in the absolute abundancesfrom below and above the tuff layers. Prior to the eruptions, the nannofossil assemblages were dominated by warmwater oligotrophic taxa, such as the rosette-like discoasters (D. saipanensis and D. barbadiensis), reticulofenestrids,
Cribrocentrum and Helicosphaera. After the eruptions, due to the temporary suspension of photosynthesis, theassemblages sharply decreased until their complete extinction in the tuff layers. The Early Oligocene nannoﬂoras weresigniﬁcantly altered, with an increasing proportion of cold-water and meso-eutrophic taxa (Coccolithus) and a ﬂux ofthe representatives of Clausicoccus. We conclude that the volcanic products––pyroclastic ﬂows, ash and gases––of thetwo consecutive eruptions covered large areas of Eastern, Central and Southern Europe, including present-day Limnos
Island to the south, and caused a substantial decrease in nannoplankton production and a lowering of the temperature.
Acknowledgements: This work was carried out within the framework of Project H24/3, funded by the National Science
Fund of Bulgaria.

INA18101

The Paleocene–Eocene Thermal Maximum Riben section
revisited (northern Bulgaria, south-eastern Europe): Newnannofossil and foraminiferal isotope data
Kristalina Stoykova
Geological Institute Bulgarian Academy of Sciences, 24 Acad. G. Bonchev Str., 1113 Soﬁa, Bulgaria; stoykova@geology.bas.bg

Torsten Vennemann
University of Lausanne, Stable Isotope Laboratory, Geopolis 4634, CH-1015 Dorigny, Switzerland

Marin Ivanov
Soﬁa University “St. Kl. Ohridski”, Faculty of Geology and Geography, 15 Tsar Osvoboditel Blvd., 1000 Soﬁa, Bulgaria

Georgi Granchovski
Geological Institute Bulgarian Academy of Sciences, 24 Acad. G. Bonchev Str., 1113 Soﬁa, Bulgaria

The occurrence of the Paleocene–Eocene Thermal Maximum (PETM) event in Bulgaria was discovered in 2005, basedon calcareous nannofossil and bulk-rock isotope data from three sections in northern Bulgaria––Kladorub, Riben andBozhuritsa (Stoykova & Ivanov, 2005). Since then, studies have continued in order to investigate the composition of
the nannofossil assemblages and the biotic response of the nannoplankton communities to the extreme global warming
during the PETM, as well as to document essential changes in the δ13C and δ18O compositions in the Paleocene/Eocene
boundary interval.
Here, we present the results from the revisited Riben section (central northern Bulgaria), where two parallel, slightly
overlapping new trenches have been excavated on the right-hand side of the abandoned quarry. High-resolution sampling,
every ~25 cm, was performed through the entire NP9 zone and PETM interval. The total number of samples analysedfor calcareous nannofossils and isotope geochemistry (δ13C and δ18O) was 35. The δ13C and δ18O measurements were
performed on isolated (Cibicidoides) foraminifera tests. The preliminary nannofossil biostratigraphy showed the relativecompleteness of the section across the Paleocene/Eocene boundary. The sedimentology suggested that deposition likely
took place in a middle-shelf setting.
The pre-PETM nannofossil assemblages were rich and diversiﬁed, comprising, among others, abundant Coccolithus
and Toweius species. These two genera dominated over Discoaster representatives. The onset of the warming was
expressed geochemically by a sharp negative δ13C excursion (CIE) from -0.05 to -4.90‰, and by a similar negative
δ18O excursion, but on a smaller scale (from -4.11 to -5.72‰, Sample R23). Moreover, it was marked by a decrease in
the carbonate content of the sediments and the deposition of a clayey interval––a light beige to rusty-brown claystone,~45-cm thick. Above the base of the CIE, a speciﬁc warm-water nannofossil association was identiﬁed, represented
by abundant discoasters (D. salisburgensis, D. lenticularis, D. multiradiatus, D. araneus) and less-common coccoliths(Coccolithus pelagicus, Toweius tovae, T. serotinus). Other stratigraphically important species––Rhomboaster bramlettei
and R. calcitrapa––exhibited rare occurrences in the core of the PETM interval.
Above the PETM, a normal biostratigraphic succession of NP10, NP11 and NP12 was documented. Additional
samples from the upper portion of the PETM were taken, and further investigations are underway. Acknowledgements:
This work was carried out within the framework of the National Science Program ‘Environmental Protection andReduction of Risks of Adverse Events and Natural Disasters’ (Agreement No. D01-279/03-12-2021).
References
Stoykova, K. & Ivanov, M. 2005. First data on the presence of the Paleocene–Eocene Thermal Maximum in Bulgaria. Comptes Rendus de l’Académie
Bulgare des Sciences, 58(3): 297–302.

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Campanian–Maastrichtian boundary interval at Beloptichene(Kula tectonic unit, north-western Bulgaria): Newnannofossil data
Georgi Granchovski, Kristalina Stoykova
Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Soﬁa, Bulgaria; georgi2801@geology.bas.bg, stoykova@
geology.bas.bg

Based on detailed calcareous nannofossil biostratigraphy and stable isotope analyses, Stoykova et al. (2020) recently
recognised the presence of the Campanian–Maastrichtian Boundary Event (CMBE), and possibly the Late Campanianand Mid-Maastrichtian Events, for the ﬁrst time in Bulgaria, at Kladorub (north-western Bulgaria). This has sparked
interest in the search for other complete sections of the Campanian–Maastrichtian boundary interval that may record
Late Cretaceous palaeoclimatic events in the country, which is still a somewhat understudied region in this regard. In lieu
of that, the calcareous nannoﬂoras from the Upper Cretaceous–Paleogene sedimentary succession at Beloptichene (Kulatectonic unit, north-western Bulgaria) have been re-examined in order to assess their preservation and the completenessof the section.
At Beloptichene, the Upper Campanian–Maastrichtian predominantly consists of silty to ﬁne-sandy marlstones,
infrequently interbedded with sandstones and marly limestones. The sandstones are more prominently represented in
the lower part of the section. These strata are overlain by a terrigenous Danian succession of sandstones, with interbeds
of silty to ﬁne-sandy marlstones, and conglomerates that vary in thickness. The present study is primarily focused on theclay-carbonate sediments in the lower half of the section.
Samples for calcareous nannofossil investigation were taken at a 0.5–1-m resolution. The recovered assemblages
were abundant and taxonomically diverse. However, compared to the Kladorub section (Granchovski, 2019), thepreservation is poor. The majority of specimens had been affected by secondary calcite dissolution and/or overgrowth,and a large proportion of them were difﬁcult to identify. Fragmentation was also present. In terms of biostratigraphy,
the following Upper Campanian–Lower Maastrichtian (sub)zones were identiﬁed: UC15eTP (pars.), UC16aTP, UC16bTP
and UC17 (pars.). Due to an unconformity, which was not observed in the ﬁeld, UC17 (Lower Maastrichtian) was
immediately overlain by NP3 (Danian), with NP3 extending into the overlying terrigenous sediments. Thus, it was
concluded that, unlike in the Kladorub section (Stoykova et al., 2020), the geological record of the CMBE in the
Beloptichene section is incomplete. This work was carried out through the National Science Program’s ‘Environmental
Protection and Reduction of Risks of Adverse Events and Natural Disasters’ (No. 577/17.08.2018) and supported by the
MES of Bulgaria (Agreement No. D01-279/03.12.2021).
References
Granchovski, G. 2019. Calcareous nannofossils from the Upper Campanian–Maastrichtian (Upper Cretaceous) in the Kladorub Formation (Kulatectonic zone, NW Bulgaria). Geologica Balcanica, 48(1): 73–101.
Stoykova, K., Granchovski, G. & Ullmann, C.V. 2020. First data on the expression of the Campanian–Maastrichtian Boundary Event in Bulgaria:
Calcareous nannofossil and carbon isotope record. Comptes rendus de l’Académie bulgare des Sciences, 73(12): 1711–1719.

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Late Quaternary coccolith weight variations in the South
China Sea and their environmental implications
Xiang SuCAS Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou
510301, China; suxiang@scsio.ac.cn

Chuanlian Liu
State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China

Luc Beaufort
Aix Marseille University, CNRS, IRD, INRA, Coll France, CEREGE, Aix-en-Provence, France

Coccolithophores are one of the most abundant and widespread groups of calcifying plankton and have attracted extensive
study in terms of their likely response to ocean acidiﬁcation. Conﬂicting results concerning coccolithophore calciﬁcation
have been reported from both experimental and ﬁeld studies. Due to their minute size, it is difﬁcult to estimate theamount of calcite in coccoliths. Here we apply the SYRACO system to analysing the weights and lengths of coccoliths
produced by the dominant coccolithophore family Noëlaerhabdaceae. We obtained high-resolution coccolith weight
and length records of the GEO (Gephyrocapsa oceanica) and SPC (Emiliania huxleyi and small Gephyrocapsa spp.)groups from sediment core MD05-2904 in the northern South China Sea (SCS) over the past 200 kyr. A calciﬁcationindex (CI), based on coccolith weight and length, was applied to evaluate the changes in coccolithophore calciﬁcation.
The two groups of coccolith weights/CIs showed different patterns on long-term variations and during the last two
terminations. We compared the coccolith weight and CI records with the environmental variables and carbonate
chemistry parameters calculated in the same core. Our data reveals that sea-surface temperature and insolation haveweak correlations to coccolith weight and CI on long-term variations. The SPC weight/CI correlated with seawater pH
and pCO2 variations, while the GEO weight/CI were more related to nutrient variations. This implies a more signiﬁcantrole of ocean carbonate chemistry in the calciﬁcation of less-calciﬁed coccolithophores and nutrient concentration inheavier-calcifying coccolithophores.

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Inﬂuence of coccolithogenesis on coccolith size and size
distribution
Baptiste Suchéras-Marx, Sophie Viseur
Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France; Sucheras-marx@cerege.fr

Charlotte E. Walker
Department of Biology, University of York, York YO10 5DD, UK

Ian Probert
Station Biologique de Roscoff, 29680 Roscoff, France

Clara T. Bolton, Luc Beaufort
Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France

Biometry is a very common tool used by the calcareous nannofossil community, helping to differentiate species, recognise
stratigraphic intervals or identify palaeoceanographic events. Concerning the palaeoceanographic aspects, a reduction
in coccolith size is often argued to be linked to an environmental stress. However, some species have a wide variationin coccolith size within a single coccosphere, thus the reliability of this tool is questionable. We discuss the variationin coccolith size over the life-cycle of one cell. These biological observations were used to set a numerical growthmodel and discuss coccolith size distributions. The results showed that: 1) a cell can produce small and large coccoliths
depending on when the coccolith is produced during the life-cycle; 2) a direct correlation between coccolith size and cellsize is true only at the time of coccolithogenesis; 3) a coccolith in a coccosphere could be a relic of a previous life-cycle;
and 4) coccolith size may not be normally distributed. All these observations remind us that biometry is a powerful tool
only if applied with a strict methodology.

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Coccolithophore blooms identified in the western Pacificduring the mid-Brunhes dissolution interval
Hanjie Sun
CAS Institute of Oceanology, Qingdao, Shandong 266071, China; sunhanjie@qdio.ac.cn

Baizheng An
Linyi University, Linyi City, Shandong 276005, China

Tiegang Li
First Institute of Oceanography, SOA, Qingdao, Shandong 266071, China

Rongtao Sun
Shandong University of Technology, Zibo, Shandong 255049, China

Fengming Chang
CAS Institute of Oceanology, Qingdao, Shandong 266071, China

The MD06-3050 Calypso core (15º57.0943’N, 124º46.7747’E, 2967 m water depth) and MD06-3047 Calypso Squarecore (17º00.44’N, 124º47.93’E, 2510 m water depth), recovered from the western Paciﬁc, were used to constructpalaeoceanographic scenarios for the mid-Brunhes in a region with an important role in global ocean–atmospheretransfer. Coccolithophore (calcareous nannofossil) and planktonic foraminiferal assemblages were collected. The
record of coccolithophore assemblages showed similar trends in MD06-3047 and MD06-3050. The coccolithophore
assemblages had relatively high proportions of Florisphaera profunda and Gephyrocapsa spp. in both cores. These
species are abundant or present in high proportions in tropical waters. The interval from Marine Isotope Stages (MISs)
8 to 14 displayed assemblages dominated by small Gephyrocapsa, especially G. caribbeanica, the highest values
being seen in the interval covering the Mid-Brunhes Event, accompanied by a clear reduction in other tropical species.
Although the ecological interpretation of G. caribbeanica is controversial due to a clear evolutionary overprint, the highabundance of this species in the western Paciﬁc could play an important role in deep-ocean carbonate dissolution that
could be inferred from the record of the planktonic foraminifera assemblages. By analysing variations in the dominantand common species, it was found that dissolution played an important role in the preservation of the planktonic
foraminifera assemblages. The relative abundances of soluble species, such as Globigerinoides ruber and G. sacculifer,showed similar trends to variations in the planktonic foraminifera fragmentation ratios over the last 1 Myr. Contrastingly,
the relative abundances of dissolution-resistant species, such as Pulleniatina obliquiloculata, display low values during
glacial intervals, but high values in interglacials. The planktonic foraminiferal assemblage in MD06-3050 was obviously
inﬂuenced by dissolution during the Mid-Brunhes Dissolution Interval (MBDI) because it was characterised by aremarkable decrease in mixed-layer species, such as G. ruber and G. sacculifer. Due to long-term low values during
the MBDI, the planktonic foraminifera accumulation rate for all the planktonic and some common species could be
used as effective dissolution proxies in MD06-3050 at a water depth of 2967 m. However, the deep-water carbonate
concentration showed high values, except for the extremely low values during MIS 11 in MD06-3047 at a water depthof 2510 m. Based on the different responses to the deep-water carbonate preservation conditions of the coccolith bloom
event between these two nearby cores, we propose that the deep-sea carbonate chemistry in the western Paciﬁc is notinﬂuenced directly by regionally enhanced surface productivity and pore-water undersaturation, but rather by the basinwide carbonate compensation depth.

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Jurassic–Cretaceous boundary interval in the Ropice section
from the perspective of biostratigraphy, stable isotopes andpalaeomagnetism
Andrea Svobodová
Czech Academy of Sciences, Institute of Geology, Rozvojová 269, CZ-165 00 Prague, Czech Republic

Lilian Švábenická
Czech Geological Survey, CZ-118 21 Praha, Klárov 131/3, Czech Republic; lilian.svabenicka@geology.cz

Daniela Reháková
Comenius University, Faculty of Natural Sciences, Ilkovi ova 6, SK-842 15 Bratislava, Slovakia

Miroslav Bubík
Czech Geological Survey, CZ-658 69 Brno, Leitnerova 22, Czech Republic

Lucie Vaňková, Martin Košťák
Faculty of Science, Charles University, Albertov 6, CZ-128 43, Czech Republic

Petr Skupien
Technical University of Ostrava, Institute of Geological Engineering, 17 Listopadu 15, CZ-708 33 Ostrava-Poruba, Czech Republic

Tiiu Elbra, Petr Pruner
Czech Academy of Sciences, Institute of Geology, Rozvojová 269, CZ-165 00 Prague, Czech Republic

The Tithonian/Berriasian boundary in the Ropice section is situated near eský Těšín, Czech Republic. The strata
belong to the Silesian Nappe Unit of the Outer Flysch Carpathians. The boundary interval comprises turbiditic
limestones (grainstones, packstones and wackestones) interbedded with marlstones (mudstones). The limestones
contain calpionellids, calcareous foraminifera and calcareous dinoﬂagellate cysts. The mudstones provide calcareous
nannofossils, siliceous agglutinated foraminifera and organic-walled dinocysts. The lowermost Berriasian wasdetermined based on the co-occurrence of Nannoconus wintereri and an acme of Calpionella alpina.
The nannofossils were mostly etched by dissolution throughout the section. There were characteristic abundancesof the genera Watznaueria (±76%) and Cyclagelosphaera (±19%) forming the main components of the assemblages.
Stratigraphically important nannoconids, Polycostella beckmannii, Helenea chiastia and Cruciellipsis cuvillieri were
found rarely. The ﬁrst occurrence of N. wintereri conﬁrmed the NC0a subzone of Casellato and Erba (2021).
The calpionellids were relatively well preserved. A microfacies analysis revealed the presence of several index
taxa for the standard calpionellid zones and subzones, including the: latest Early Tithonian Chitinoidella Zone (Boneti
Subzone); Late Tithonian Crassicollaria Zone (Remanei, Intermedia and Colomi Subzones); and Early BerriasianCalpionella Zone (Alpina Subzone).
Small calcareous foraminifera (Spirillina, Trocholina, Lenticulina) and agglutinated foraminifera (Pseudoreophax
cisovnicensis, Pseudonodosinella troyeri, Ammogloborotalia quinqueloba, Caudammina silesica) had low
biostratigraphic value.
The dinoﬂagellate cyst association of Mendicodinium groenlandicum, Systematophora areolata and S. orbifera
of Late Tithonian age occurred in the lower part of the section. The presence of Amphorula delicata, Muderongia
longicorna and M. tabulata correlated well with the lowermost Berriasian Alpina Subzone.
The stable isotope record (δ18O, δ13C) showed mostly lower positive values for δ13C (~0.5‰ PDB), with several
negative excursions reaching ~-1.7‰ PDB, and typically negative values for δ18O (~-4.2‰ PDB). The weak δ13C signal
was consistent with the majority of the Outer Flysch Carpathian sections in the Jurassic/Cretaceous boundary interval.

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The magnetic data indicated an extensive remagnetisation, with the presence of the weathering product, goethite, along
the whole section. The average magnetic susceptibility and natural remanent magnetisation showed low values of 48 ×
10-6 SI and 0.17 mA/m, respectively. The highest susceptibility (143 × 10-6 SI) was found in Bed 15. Acknowledgements:
This research is supported by the Czech Science Foundation (Project No. 20-10035S), and accords with Research Plan
Nos. RVO67985831 and DRKVO/ GS 2018–2022. The microfacies, calpionellid and calcareous dinocyst investigations
were funded by a project of the Slovak Grant Agency (No. APVV-20-0079) and by VEGA 2/0013/20.
References
Casellato, C.E. & Erba, E. 2021. Reliability of calcareous nannofossil events in the Tithonian–Early Berriasian time interval: Implications for a revised
high-resolution zonation. Cretaceous Research, 117.

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Primary productivity, monsoon strength and coccolithexport in the north-western Bay of Bengal over the Late
Pleistocene
Phyo Thant
Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France & University of Lille, France; phyowaithant60@gmail.com

Alexis Licht, Luc Beaufort, Yves Gally, Sandrine Conrod, Clara Bolton
Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France

The South Asian Monsoon is the world’s largest hydrological phenomenon, and its seasonal winds and precipitation
impact the livelihood of billions of people on the subcontinent. Understanding its variability in the past, and the interplay between monsoon winds and precipitation, the ocean carbon cycle, and climate forcing mechanisms, is therefore ofparamount importance for the prediction of monsoons in the future.
Here, we present new high-resolution records from International Ocean Discovery Program (IODP) Site U1446 in
the Mahanadi Basin, north-western Bay of Bengal, a region strongly inﬂuenced by freshwater runoff from India. This
freshwater runoff, which reaches a maximum during the late summer–early autumn, following summer monsoon rains,inﬂuences the upper water-column structure and induces strong stratiﬁcation, with impacts on marine primary productivity. Using new records of coccolith assemblages, masses and accumulation rates from Site U1446 sediments spanningthe last ~80,000 years, we investigated the relationship between monsoon strength and runoff (based on independent
proxies), coccolithophore productivity and coccolith-carbonate accumulation. We found that, during the Last Glacial
Maximum, productivity and coccolith-carbonate export at Site U1446 were enhanced relative to the Holocene. We
also investigated the millennial-scale variability of coccolithophore productivity in the Holocene, and its link to North
Atlantic climate.

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Coccolithophore responses to palaeoenvironmental
variability in the Gulf of Cadiz (IODP Site U1387) throughMISs 48–45
Samanta Trotta, Maria Marino
Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari Aldo Moro, Bari, Italy; samanta.trotta@uniba.it

Antje Helga Luise Voelker, Teresa Rodrigues
Instituto Português do Mar e da Atmosfera, Divisão de Geologia e Georecursos Marinhos, Alges, Portugal & Centro de Ciências do Mar (CCMAR),
Universidade do Algarve, Portugal

José-Abel Flores
Department of Geology, University of Salamanca, Salamanca, Spain

Patrizia Maiorano, Angela Girone, Marina Addante
Dipartimento di Scienze della Terra e Geoambientali, Università degli Studi di Bari Aldo Moro, Bari, Italy

Barbara Balestra
Environmental Science Department, American University, Washington, DC 20016, USA & Paleobiology Department, National Museum of Natural
History, Smithsonian, Washington, DC 20560, USA

High temporal resolution analyses (300 years) of coccolithophore assemblages through MISs 48–45 were carried out toimprove the dataset on climate variability during the ‘41-kyr world’, prior to the Mid-Pleistocene Transition. Sediment
samples were recovered from IODP Site 339-U1387, from a water depth of 558 m on the middle slope of the Faro Driftin the Gulf of Cadiz (36º48.321”N, 7º43.1321”W).
Thirty-three taxa were identiﬁed to the genus, species and subspecies level. Gephyrocapsids were the dominantgroup, contributing more than 85%. Reworked coccoliths and lithic or mineral elements (>10 µm) were counted separately to monitor variability in the terrigenous supply. Principal component analysis showed that temperature and productivity were the ﬁrst and second factors, respectively, controlling coccolithophore assemblage composition.
The abundance ﬂuctuations of key taxa, such as Gephyrocapsa caribbeanica and Coccolithus pelagicus ssp. pelagicus, warm-water taxa, and large Gephyrocapsa (>5.5 µm), as well as of the reworked and lithic elements, allowed therecognition of glacial (MISs 48–46) and interglacial (MISs 47–45) phases, in agreement with the Globigerina bulloides
δ18O record at the study site, reﬂecting the southward/northward migration of the Portugal/Iberian Poleward Currents,
respectively. Short-term increases in C. pelagicus pelagicus abundances during the glacial phases pointed to the presence of polar meltwater, also evidencing a millennial-scale climatic variability during the Early Pleistocene.
The increases in coccolithophore productivity (CP) during short intervals in the glacial phases (MIS 48 and MIS 46)
have been related to enhanced northerly wind intensity, as a consequence of the expansion of the Northern Hemisphere
continental ice-sheets, leading to surface-water mixing and increased nutrient availability. Brief CP increases during
the interglacial phases (MIS 47 and MIS 45) occurred during insolation maxima/precession minima that promoted anincrease in rainfall and river runoff, favouring enhanced riverine nutrient supply. The co-occurrence of sapropels in theeastern Mediterranean Sea during the interglacial CP increases at the studied site supports the orbitally controlled highprecipitation-condition hypothesis, and highlights a correspondence between similar climatic conditions west and eastof the Gibraltar Strait during the Early Pleistocene, as observed in Middle Pleistocene intervals (Voelker et al., 2015).
References
Voelker, A.H.L., Salguiero, E., Rodrigues, T., Jiminez-Espejo, F.J., Bahr, A., Alberto, A., Loureiro, I., Padilha, M., Rebotim, A. & Röhl, U. 2015.
Mediterranean outﬂow and surface-water variability off southern Portugal during the Mid-Pleistocene Transition––A snapshot of Marine Isotope
Stages 29 to 34 (1010–1135 ka). Global and Planetary Change, 133: 223–237.

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Morphological and crystallographic variation of coccoliths in
the Umbilicosphaera (Calcidiscaceae) lineage
Masayuki Utsunomiya
Geological Survey of Japan, AIST, 1-1-1, Higashi, Tsukuba 305-8567, Japan; m.utsunomiya@aist.go.jp

Toshihiro Kogure
Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033,
Japan

The morphology of placolith-type coccoliths is unique to the given species, characterised by the size of the distal andproximal shields, diameter of the central opening and shape of the suture lines, etc. These characters are basicallydetermined by the shapes of the organic base-plate and coccolith vesicle enfolding the plate, and the crystal orientationof the initially precipitated calcite around the rim of the plate. Analysis using high-resolution scanning electron
microscopy (SEM) and electron back-scattered diffraction (EBSD) can provide an understanding of the relationshipbetween the crystallographic orientations of the shield elements and the morphologies of the coccoliths (e.g. Saruwatari
et al., 2006). Such analysis allows us to understand what controls the species-speciﬁc morphology and what has changedin the evolutionary lineage of the coccolithophore. For this purpose, SEM–EBSD analyses of several taxa with direct
ancestor–descendant relationships might be expected, but there are no examples of such studies, to our knowledge. The
genus Umbilicosphaera, which is the subject of the present study, has a fossil record that runs from the Late Paleocene.
Umbilicosphaera patera (newly described by Utsunomiya et al., 2021) is considered to be the most recent common
ancestor of the extant species U. sibogae. The diversiﬁcation of U. sibogae from U. patera occurred during the Pliocene.
We obtained morphometric data and measured the c- and ai-axis orientations of the distal shield elements around thecentral opening of these two species using SEM–EBSD. The c-axis of the distal shield elements of U. patera inclined
upwards at ~55º from the coccolith plane, and one of the ai-axes was roughly parallel to the coccolith plane. On theother hand, the c-axis of the distal shield element of U. sibogae inclined upwards at ~65º from the coccolith plane. Thisdifference in the crystal orientation explains the nearly ﬂat distal shield and steep inner slope around the central opening
in the morphology of U. patera compared to those of U. sibogae, assuming that the facets of the distal shield elements
consist of {104} planes of calcite.
References
Saruwatari, K., Ozaki, N., Nagasawa, H. & Kogure, T. 2006. Crystallographic alignments in a coccolith (Pleurochrysis carterae) revealed by electron
back-scattered diffraction (EBSD). American Mineralogist, 91: 1937–1940.
Utsunomiya, M., Hagino, K. & Tanaka, Y. 2021. Speciation of extant Umbilicosphaera (Prymnesiophyceae) during the Pliocene. Marine
Micropaleontology, 169: 102037.

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The Neogene Central American Seaway
Felipe Vallejo, Andrés Pardo-Trujillo, Ángel Barbosa-Espitia, Daniela
Aguirre, Sergio A. Celis, Carlos A. Giraldo-Villegas, Ángelo Plata, Raúl
Trejos-Tamayo, Andrés Salazar-Ríos, Alejandro Arenas
Instituto de Investigaciones en Estratigrafía, Universidad de Caldas, Manizales, Colombia; diego.vallejo@ucaldas.edu.co

José-Abel Flores
Departamento de Geología, Universidad de Salamanca, Spain

Marie-Pierre Aubry
Department of Earth and Planetary Sciences, Rutgers University, USA

Fabián Gallego, Eduardo Delgadillo
Instituto de Investigaciones en Estratigrafía, Universidad de Caldas, Manizales, Colombia

David Foster
Department of Geologic Sciences, University of Florida, USA

Two of the world’s largest oceans––the Paciﬁc and Atlantic––have been connected through a sea passage called theCentral American Seaway (CAS). The closure of this passage and separation of the two oceans have been impacted by
the ongoing interaction of the Caribbean and South American Plates, readjusting oceanic currents and creating the only
land bridge between South and North America. The modalities and timing of the closure during the Neogene have been
the objectives of many studies, resulting in two main proposals, one for the late closure of the shallow seaway and theother for the early closure of the deep-sea connection. A Late Pliocene cessation of the ﬂow of shallow oceanic waters
between the Atlantic and Paciﬁc Oceans has been the classic interpretation. A Middle Miocene closure of the deepoceanic seaway along the tectonic boundary between the Panamá Arc and the oceanic rocks of the Western Cordillera ofColombia is a more recent and controversial interpretation. However, until now there has not been any direct geologicalevidence from the tectonic boundary to support either interpretation. This new study, which involved ﬁeldwork along
the Panamá Arc and western South American tectonic boundary, has revealed a stratigraphic record of Miocene marine
sediments that were deposited in the Central American Seaway along the suture zone (CASsz). Although highly deformed
and fractured, these sediments constitute the only known direct evidence of the geological history along the CASsz.
Micropalaeontological, including calcareous nannofossils, U–Pb detrital geochronological and ichnological data fromthese deposits attest to a progressive shallowing during the latest Early to earliest Middle Miocene (16.4–15.1 Ma).
Our data indicate that marine conditions were already shoaled (<120 m depth) in some sectors of the CASsz, possibly
implying that water depth exchanges between the Atlantic and Paciﬁc oceans were already affected by closure during
the Early to Middle Miocene. When we combine our results with previous studies from Central America and western
Colombia, our research supports several parts of the Panamá Arc having shoaled to neritic palaeodepths by the Middle
Miocene, resulting in a perturbed ﬂow of deep water across the arc and implying that the CAS should not be restricted tothe suture zone (CASsz). Our ﬁndings agree with the view that the onset of the Atlantic overturning circulation preceded
the Pliocene intensiﬁed cooling (2.5 Ma) of the western Northern Hemisphere by several million years (~13 Myr). The
CAS was represented by different straits that closes at different times, probably vanishing in the suture zone (CASsz)
by the Middle Miocene (between 15 and 12 Ma), as previously proposed. Nevertheless, well-calibrated stratigraphic
sections older than the Late Miocene from Central America and western Colombia are still needed in order to better
understand the geological evolution of the CAS prior to the well-known shallow oceanic disruption of the Pliocene.

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New Middle Miocene genus Olladiscoaster
Osman Varol
Rhos-on-Sea, North Wales, UK; osman@varol.com

Andrew R. Bowman
Missouri City, TX, USA

Olladiscoaster is jar-shaped and characterised by having a kite- or boomerang-shaped distal cover––the primary
criterion for distinguishing it from Discoaster. The species’ outline or central-area can be circular, hexagonal or stellate.
The bulging proximal side possesses ridges and is often decorated with a stellate, hexagonal or star-shaped proximal
knob, although the knob may be absent in rare cases. The sutural ridges formed by deep cavities rise towards thecentre and are coated with a boomerang- or kite-shaped distal cover. Olladiscoaster has segments that often display
vestigial free length or lack free length entirely. Species randomly settle in the plan or distal view because they possessa similar height:width ratio. Olladiscoasters are extinct in plan view (the c-axis is aligned with the microscope axis), butbirefringent in side view, displaying strong interference colours. The samples derived from various commercial oil wellsin the Gulf of Mexico, IODP Leg 354, Site U1451B, DSDP Leg 154, Site 926A and the USGS–NASA Langley corefrom Hampton, VA, USA. They were studied using a light-microscope (LM) and the mobile-mount technique, and witha scanning electron microscope (SEM). The different proﬁles for most of the species were mapped.
Olladiscoaster ranges from 14.75 to 11.90 Ma in the Middle Miocene (Zones NN5–NN7). Diverse and highabundances of Olladiscoaster were noted at 13.50 and 13.21 Ma (in NN6). Three groups of Olladiscoaster wererecorded, primarily based on the characteristics of the segments. Other criteria used include the presence or absence ofa proximal knob and the morphology of the knob when present. The O. virginianus group is characterised by having
segments with free length and a hexagonal central-area with a boomerang-shaped distal cover. This group is related to
the Discoaster musicus group and possibly evolved from them. The O. molae group has segments with vestigial free
length and a stellate outline (except for O. vestiguum, which is hexagonal) and a proximal knob. The O. bordii group has
segments with no free length and circular outlines (except for O. perplexus, which is hexagonal).
Ten new species––O. artatus, O. bordii, O. cruzii, O. lepidus, O. molae, O. perplexus, O. self-trailiae, O. superbus, O.
vestiguum and O. zucciae have been described. Three new combinations––O. catinatus, O. tokerae and O. virginianus––
have been introduced.

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Surface-sediment coccolith assemblages and Emiliania
huxleyi morphotype calcification across the Drake Passage,
Southern Ocean
Nele Manon Vollmar
Previously University of Bremen, Department of Geosciences, Klagenfurter Strasse 2-4, 28359 Bremen, Germany & now NORCE Norwegian
Research Centre, Climate & Environment, Bergen, Norway; nevo@norceresearch.noKarl-Heinz Baumann
University of Bremen, Department of Geosciences, Klagenfurter Strasse 2-4, 28359 Bremen, Germany; baumann@uni-bremen.deMariem Saavedra-Pellitero
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK

Iván Hernández-Almeida
Department of Earth Science, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland

The physical and biogeochemical properties of the Southern Ocean (SO) are experiencing rapid and profound changes
that may inﬂuence the distribution and composition of pelagic plankton communities. The most proliﬁc carbonateproducing phytoplankton group––the coccolithophores––play an important role in SO biogeochemical cycles. Although
records of (sub-)fossil coccolith assemblages constitute invaluable indicators for palaeoenvironmental reconstructions,knowledge on the SO is scarce.
This study investigated the coccolith assemblages preserved in surface sediments across the Drake Passage, retrieved
during the R/V Polarstern Expedition PS97. We focused on the coccolith response to steep environmental gradients
across the frontal system of the Antarctic Circumpolar Current. We also examined the morphological diversity ofEmiliania huxleyi, emphasising biogeographical variability, coccolith size and calcite carbonate-mass estimations.
North of the Polar Front, the surface sediments provide suitable material for reconstructing the overlying surfaceocean conditions. Comparatively high coccolith abundances and species diversity occurred especially south of the Polar
Front. Here, further factors, such as temporarily thriving coccolithophore communities in the surface waters or thetransport of settling coccoliths via surface and bottom currents and eddies, have inﬂuenced the (sub-)fossil coccolithassemblages. Additionally, deeper samples in the southern part of the study area were particularly affected by selective
carbonate dissolution.
We identiﬁed ﬁve E. huxleyi morphotypes (A, A overcalciﬁed, R, B/C and O). The E. huxleyi morphologies reﬂect
diverging biogeographical distributions, trending towards smaller and lighter coccoliths to the south, and emphasising
the importance of documenting those morphologies in relation to changing environmental conditions in order to assess
their response to projected environmental change in the SO.

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Interregional correlations and sea-level changes in Middle
Paleocene–Early Eocene of the eastern Tethys Sea (CentralAsia): Calcareous nannofossil evidence from the western
Tarim Basin, north-western China
Xuejiao Wang
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Xueyuan Road 29, Haidian District, Beijing
100083, China & Université Lyon, UCBL, ENSL, UJM, CNRS, UMR 5276 LGL-TPE, F-69622 Villeurbanne, France & Institut Universitaire deFrance, Paris, France; xuejiaowang410@hotmail.com

Emanuela Mattioli
Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement (UMR 5276, CNRS) Université Lyon 1, Ecole Normale Supérieure Lyon,
Campus scientiﬁque de la Doua, 69622 Villeurbanne, France

Dangpeng Xi
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Xueyuan Road 29, Haidian District, Beijing
100083, China

Calcareous nannofossil assemblages from the interval covering the Middle Paleocene to Early Eocene (P/E), studiedin sediments from two sections in the western Tarim Basin (Bashibulake and Kuzigongsu), indicate a record of the
Paleocene–Eocene Thermal Maximum (PETM) inscribed in a transgression–regression cycle. The transgression wasinterpreted on the basis of species richness and abundance increasing gradually from the base of the Qimugen Formation(dated as NP7–NP9a, Thanetian), in which the ﬁrst occurrences of Heliolithus riedelii and Discoaster multiradiatus
have been recorded. The turnover of the sea-level cycle coincided with increasing Discoaster spp. amounts near the P/Eboundary (NP9b–NP10), which was dated by the occurrence of assemblages containing Rhomboaster spp. and the D.
araneus group. Evidence of regression, indicated by low nannofossil abundances and diversity, was observed at the topof the Qimugen Formation (NP10), coinciding with assemblages characterised by rapidly increasing Micrantholithus
spp. and constantly low abundances and diversity of nannofossils. The sea-level change in the Bashibulake section
occurred close to the boundary of NP9a/NP9b, and was recorded earlier than in the Kuzigongsu section, where an abrupt
decrease in abundance of Discoaster spp. was observed below the dissolution zone, while an increase in M. astrum
was noted in the aftermath of the event. Interregional correlations, established thanks to the variations in calcareous
nannofossil assemblages in the two sections, suggest that sea-level changes in the southern part of the Tarim Basinoccurred earlier than to the west.

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Regression of the Tethys Sea from Central Asia during
the Middle to Late Eocene: Evidence from calcareous
nannofossils of the western Tarim Basin, north-western
China
Xuejiao Wang
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Xueyuan Road 29, Haidian District, Beijing
100083, China & Université Lyon, UCBL, ENSL, UJM, CNRS, UMR 5276 LGL-TPE, F-69622 Villeurbanne, France & Institut Universitaire deFrance, Paris, France; xuejiaowang410@hotmail.com

Dangpeng Xi
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Xueyuan Road 29, Haidian District, Beijing
100083, China

David K. Watkins
Department of Earth and Atmospheric Sciences, University of Nebraska, Lincoln, NE 68588-0340, USA

Jean M. Self-Trail
Florence Bascom Geoscience Center, US Geological Survey, 926a National Center, Reston, VA 20192, USA

Calcareous nannofossil assemblages from Middle to Upper Eocene sediments of the western Tarim Basin indicate two
important episodes of marine incursion into the basin. The ﬁrst episode represents a period of shallowing upwards in the
Wulagen Formation, and is dated as Zone CNE13 (Lutetian) by the co-occurrence of Discoaster bifax, Chiasmolithus
solitus and common Reticulofenestra umbilicus. The presence of a diverse assemblage of discoasters in the basal Wulagen
Formation suggests deposition occurred in oligotrophic, warm waters with a connection to the open ocean. Progressive
shallowing over time led to the formation of a restricted basin in which only Coccolithus pelagicus could survive. The
second major episode of marine incursion is preserved in the middle part of the Bashibulake Formation, which is dated
as Zone CNE17 (Bartonian/Priabonian) based on the presence of common Cribrocentrum erbae. The interval between
the two marine incursions was dominated by subaerial exposure and evaporation, resulting in the deposition of gypsum
at the top of the Wulagen Formation. Although maximum regression at the end of the Lutetian was followed by sea-level
rise at the beginning of the Bartonian, globally, it is clear that local tectonics played a crucial role in regional marine
incursions into the Tarim Basin during deposition of the Wulagen Formation.

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Evolution of Miocene calcareous nannofossil assemblages asa response to palaeoceanographic changes in the northern
South China Sea
Yasu Wang
College of Oceanography, Hohai University, Nanjing 245700, China; wys199187@163.com

Hoshina Kazuki
Department of Earth and Environmental Sciences, Yamagata University, Yamagata 990-8560, Japan

Hong Su
College of Life Science and Technology, Jinan University, Guangzhou 510632, China

Richard W. Jordan
Department of Earth and Environmental Sciences, Yamagata University, Yamagata 990-8560, Japan

Shijun Jiang
College of Oceanography, Hohai University, Nanjing 245700, China

The South China Sea (SCS) is the largest marginal sea in the western Paciﬁc, and is located in the west Paciﬁc warm pool
(WPWP) and in a key region of global thermohaline circulation. The thick sedimentary sequence in the SCS represents
a complete and continuous record of tectonic, palaeoclimatic and palaeoceanographic changes, therefore making the
SCS an important area for studying Cenozoic palaeoenvironments. Here, we selected the continuous sediment archives
obtained from International Ocean Discovery Program (IODP) Site U1501 on the northern margin of the SCS for
biostratigraphic and palaeoceanographic study. A quantitative analysis of the calcareous nannofossil assemblages was
performed, in combination with CaCO3 (wt%) measurements, to investigate the palaeoceanographic changes in the SCS
between 15 and 5 Ma.
Totals of 117 calcareous nannofossil species in 32 genera were identiﬁed in the 217 samples from IODP Site U1501.
The common taxa included Reticulofenestra (R. minuta, R. minutula, R. haqii, R. pseudoumbilicus), Florisphaera
profunda，Cyclicargolithus ﬂoridanus，Discoaster (D. berggrenii, D. brouweri, D. pentaradiatus, D. quinqueramus, D.
variabilis), Helicosphaera carteri, Calcidiscus leptoporus, Coccolithus pelagicus, Sphenolithus (S. abies, S. moriformis,
S. heteromorphus) and Umbilicosphaera (U. jafari，U. rotula). Small Reticulofenestra spp. were predominant throughout
the Middle Miocene, indicating high marine productivity. The Umbilicosphaera, Discoaster and large Reticulofenestra
spp. (R. pseudoumbilicus, R. perplexa) abundances showed rapidly increasing trends from the Middle to Late Miocene,
their high abundances possibly indicating low-fertility conditions. The CaCO3 (wt%) and total shield index decreased inthis interval, reﬂecting the decrease in marine productivity and enhancement of carbonate dissolution, which coincidedwith the carbonate crash. Then, the abundance of small Reticulofenestra spp. and CaCO3 (wt%) gradually increased
synchronously, indicating that marine productivity gradually recovered and carbonate preservation improved.
The evolution of the calcareous nannofossil assemblages mentioned above reﬂects the palaeoceanographic changes
that occurred from the Middle Miocene to Early Pliocene in the SCS. During the Middle Miocene, the Indonesia Seaway
was not completely closed, and therefore the thermocline was shallow and surface mixing was strong, which may haveprovided sufﬁcient nutrients to maintain high marine productivity. Then, at the Middle/Late Miocene boundary, theproto-WPWP was formed due to the constriction of the Indonesian Seaway, which deepened the thermocline, weakened
the surface mixing and reduced the nutrient supply from the deep sea, thereby reducing productivity and biogenic
carbonate production, leading to the carbonate crash event. Subsequently, enhanced monsoon circulation and continental
weathering led to an increase in the nutrient supply, which increased marine productivity from the Late Miocene to
the Pliocene, leading to the biogenic bloom event in the SCS. Acknowledgements: This work was jointly funded by
the National Natural Science Foundation of China (Nos. 41976045, 41888101) and the Southern Ocean Science andEngineering Guangdong Laboratory (Zhuhai) Innovation Team Construction Project (No. 311021002).

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A high-resolution depth profile of coccolithophores inoligotrophic waters of the North Atlantic gyre
Amos WinterEarth and Environmental Systems, Indiana State University, Terre Haute, IN 47809, USA; amos.winter@indstate.edu

Hartmut Schulz
Faculty of Sciences and Mathematics, Tübingen University, Germany

Jeremy R. Young
Earth Sciences, University College London, Gower Street, London, UK

Richard Lotspeich
Department of Economics, Indiana State University, Terre Haute, IN 47809, USA

Liam Hood, Josue J. Millan, Christian Sizemore
Earth and Environmental Systems, Indiana State University, Terre Haute, IN 47809, USA

We report abundances and vertical distributions of coccolithophore species from water samples retrieved on 28 January,
2015 by the R/V Meteor during the M113/2 cruise, at Station #39, located at ~31.46ºN, 44.44ºW in the North Atlantic
Gyre. Whenever possible, at least 300 specimens from 24 depths, from the surface to 400 m, were evaluated by scanningelectron microscope to determine the community composition. This location is representative of oligotrophic regionsof oceans with a deep Chl-a maximum at 120 m, where we observed abundant coccolithophores. Oligotrophic regions
account for 70% of the photosynthetic volume of the oceans. We are seeking to understand the contribution of thecoccolithophores in this region to the biogeochemical cycling of carbon.

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The V/R model of heterococcolith biomineralisation 30
years on: Unanswered questions and continuing relevance
Jeremy R. Young, Paul R. Bown
Earth Sciences, University College London, London WC1E 6BT, UK; jeremy.young@ucl.ac.uk

The V/R model of coccolith biomineralisation was ﬁrst published by Young et al. (1992)––so, 30 years ago. Broadly,
this consisted of: 1) the observation that the biomineralisation of heterococcolith rims commonly commenced with thenucleation of calcite microcrystals with alternately sub-vertical (V) and sub-radial (R) crystallographic c-axis orientations;2) the observation that this pattern was conserved through the 230-Myr evolutionary history of heterococcoliths and so
likely provided a key to studying the homology between taxa; 3) a hypothesis that the nucleation might be controlled bya plicated macromolecular template located around the rim of the cellulosic baseplate.
The model has generally held up well, with support both from its application across the biodiversity of extant andfossil heterococcoliths, and from detailed studies of biomineralisation in particular species. Nonetheless, numerous
questions posed by the model remain unanswered and, perhaps more surprisingly, many taxonomists largely ignore
it. This talk will discuss some of the unanswered questions related to the V/R model and why it continues to be a key
tool in understanding coccolith evolution and taxonomy. Unanswered questions include: Is there a precursor template
for the nucleation template, and, if not, how does the biological system precisely control the orientation and spacingof the nuclei? Are the V/R orientations precisely 90º apart or does this vary? Nucleation spacing varies around the rimof coccoliths, is this geometrically determined or altered by design? Is the variation in nucleation spacing and chirality
phylogenetically signiﬁcant? Nucleation in holococcoliths, in many heterococcolith central-areas and in many nannoliths
does not show the V/R pattern––are these radically different biomineralisation modes or are they modiﬁcations of thetypical V/R mode? Do the Syracosphaeraceae really show a V/R/T pattern of nucleation?
The relevance of the V/R model to practical taxonomy will be discussed with reference to Palaeogene placoliths,
such as Aliculosphaera, Centumgemina, Ericsonia, Hornibrookina and Toweius. More generally, it will be argued that
nannofossil taxonomy requires: 1) tracing of the interconnections of elements to form crystal units; 2) determination of
the c-axis orientation of crystal units; and so 3) integrated use of electron microscopy and light microscopy (including
the use of accessory plates and phase-contrast).

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Nannotax: Bibliography project and other updates
Jeremy R. Young
Earth Sciences, University College London, London WC1E 6BT, UK; jeremy.young@ucl.ac.uk

Ines Galović
Croatian Geological Survey, Sachsova 2, 10000 Zagreb, Croatia

Richard W. Howe
Ellington Geological Services, 1414 Lumpkin Rd, Houston, TX 77043, USA

Shijun Jiang
College of Oceanography, Hohai University, Nanjing, China

Baptiste Suchéras-Marx
Aix Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France

The Nannotax website was ofﬁcially launched in something close to its current form at the INA13 conference inWashington in 2013. Since then, it has both become the prime online resource for the taxonomy of living and fossil
coccolithophores and has also been continuously developed, expanded and updated. This was a lockdown-compatible
activity and so has continued through the last few years. General updates since the last INA conference in 2019 haveincluded adding around 5000 more images, from about 150 publications, 200 new taxon descriptions in the Farinacci& Howe catalogue and many edits to the main database, but with more still to do. Three signiﬁcant changes to the data
structure and capability have also been made, and these will be outlined in this talk.
1. Image sorting and searching. The images are now classiﬁed by image type, such as SEM–distal, SEM–coccosphere,
LM–coccosphere, etc. This is used to sort images on the pages. In parallel, new image search tools have been developed.
Together, these allow the increasingly large collections of images for single taxa to be used for research.
2. Advanced search. The original advanced-search system introduced in 2017 was based on a very large vocabularyof descriptive terms and did not prove very useful or popular. This has now been replaced by a simpler set of terms witha graphic interface, which is, hopefully, quicker and easier to use, while still allowing rapid narrowing of the ﬁeld of
possible identiﬁcations.
3. Expanded bibliography and PDF collection. This has been a major project, carried out with Baptiste SuchérasMarx, Shijun Jiang and Ines Galović. The objective was to develop a rather comprehensive bibliography of the literature
on nannofossils and nannoplankton and a linked PDF collection. This required improved databasing of the bibliography,
databasing of the copyright/open access status of journals, and developing new scripts to link PDFs to references. In
parallel, bibliographies and PDF collections from multiple sources have been merged and cleansed. As a result, theNannotax bibliography now contains 4630 references (vs 1900 in 2019), with PDF copies available for 3400 of these.

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Evolution of upper seawater stratification in the South
China Sea central basin during the Late Miocene
Xinquan Zhou, Chuanlian Liu
Tongji University, State Key Laboratory of Marine Geology, 1239 Siping Road, Shanghai 200092, China; xinquan_zhou@tongji.edu.cn

The South China Sea (SCS)––the largest semi-enclosed marginal sea in the western Paciﬁc Ocean––is an excellent
site for exploring tropical seawater evolution in response to tectonic activity in geological time. Most of the previous
studies on long time-scales have relied on sediment cores obtained from its continental margins. Here, we provide a Late
Miocene record of upper seawater stratiﬁcation reconstructed using variations in calcareous nannofossil assemblages
from the SCS central basin, which has an average water depth of 4700 m. The Upper Miocene unit of IODP Site U1433(studied here) consists of alternate carbonate and clay layers. The genesis of these carbonate layers by turbidity currents
was supported by both the sedimentology and the presence of reworked coccoliths. The clay layers can be viewed as
pelagic deposits, and thus can be used for palaeoenvironmental reconstruction. A calcareous nannofossil biostratigraphyof the Late Miocene (~10 to 5 Ma) is provided, based on the studied clay samples.
Calcareous nannofossil abundances and assemblages were used to reconstruct the evolution of the upper seawater
structure. The absolute abundance of total calcareous nannofossils showed a signiﬁcant increase at ~8 Ma associatedwith changes in the relative contributions of small reticulofenestrids and oligotrophic species. Our results indicate thatthe upper seawater shifted from strongly stratiﬁed to well-mixed accompanied by an increase in pelagic productivity at~8 Ma. This shift was due to the closure of the Indonesian Seaway, an enhanced summer monsoon over the SCS, andhigher Mekong river input driven by the uplift of the Vietnam Central Highland.

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Mid-Eocene thermals record in the Istrian Paleogene Basin(Outer Dinarides, Croatia), Neotethys
Renata Lukić
Department of Geology, Faculty of Science, University of Zagreb, Horvatovac 102b, 10000 Zagreb, Croatia

Stjepan Ćorić
Geological Survey of Austria, Neulinggasse 38, 1030 Vienna, Austria

Ines Galović*, Marija Horvat
Croatian Geological Survey, Sachsova 2, 10000 Zagreb, Croatia; ingalovic@hgi-cgs.hr

Katja Mužek, Đurđica Pezel, Vlasta Ćosović
Department of Geology, Faculty of Science, University of Zagreb, Horvatovac 102b, 10000 Zagreb, Croatia

Several short sections from Istria, northern Adriatic (Racani––Rac, <5 m; Jakomići––J, ~6 m and Jak, ~2 m), were studied
micropalaeontologically and geochemically. The top Nannotetrina spp. (N. cristata) (42.97 Ma) and base common
Reticulofenestra umbilicus (42.3 Ma) point to Zone NP16 (Martini, 1971) and the Lutetian MNP16A (Fornaciari et al.,2010; Agnini et al., 2014), which agree with the foraminiferal E10/E11 zonal boundary in the Racani section (Berggren &Pearson, 2005). This interval is known as the Late Lutetian Thermal Maximum (Westerhold et al., 2020). The interpreted
peak climatic condition is reﬂected in the relatively high species richness (73) and the rapid deposition of two organicrich intervals (7.25% TOC), which may be associated with the increase in the concentration of sulphur (0.29% TOC/S)
and low concentration of Mn (0.09%), implying low-oxygen, possibly dysoxic, bottom-water conditions (Spofforth
et al., 2010 and references therein). The warm-water species Cyclicargolithus ﬂoridanus dominated (up to 52%) the
assemblages, indicating meso-oligotrophic conditions (Toffanin et al., 2011).
In the Mediterranean, the base Furcatolithus obtusus (39.63 Ma) coincides with the top Sphenolithus spiniger (39.63
Ma), which was recorded at the top of Section J, indicating Bartonian Subzone MNP16Bc (= NP17), which indicates
Chron C18n2n (Fornaciari et al., 2010). The domination of the warm-water Reticulofenestra bisecta (21%) points tothe enhanced eutrophic conditions that characterised the carbon isotope excursion phase of the Middle Eocene Climatic
Optimum (MECO) (D’Onofrio et al., 2021 and reference therein), with continued high (71) species richness.
The base Furcatolithus obtusus at the base (in the ﬁrst metre) of the Jak section deﬁnes the base of Subzone
MNP17A, which agrees with the top S. spiniger (which occurred in the second metre of the section). The warm-water
Reticulofenestra producta increased (by up to 25%), suggesting more shallow and mesotrophic conditions (Wade &Bown, 2006), with the decreased species richness (65) characteristic of the post-MECO phase (D’Onofrio et al., 2021).
The composition of the planktonic foraminiferal assemblages (predominantly thermocline-dwelling Subbotina andcommon subsurface-dwelling Turborotalia) and the low proportion of smaller benthic foraminifera (15% in J, 3.8–5.4%
in Jak and 20% in Rac) indicate eutrophic to mesotrophic conditions in the lower bathyal (Murray, 1991), stratiﬁed watercolumn (Pearson et al., 2001). This study was undertaken within the framework of the Croatian Science Foundation
Project IP-2019-04-5775 BREEMECO.
References
Agnini, C., Fornaciari, E., Rafﬁ, I., Catanzariti, R., Pälike, H., Backman, J. & Rio, D. 2014. Biozonation and biochronology of calcareous nannofossils
from low and middle latitudes. Newsletters on Stratigraphy, 47: 131–181.
Berggren, W.A. & Pearson, P. 2005. A revised tropical to subtropical Paleogene planktonic foraminiferal zonation. Journal of Foraminiferal Research,
35: 279–298.
D’Onofrio, R., Zaky, A., Frontalini, F., Luciani, V., Catanzariti, R., Francescangeli, F., Giorgioni, M., Coccioni, M., Ozcan, E. & Jovane, L. 2021.
Impact of the Middle Eocene Climatic Optimum (MECO) on foraminiferal and calcareous nannofossil assemblages in the neo-Tethyan Baskil
section (eastern Turkey). Paleoenvironmental and paleoclimatic reconstructions. Applied Sciences, 11.

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Fornaciari, E., Agnini, C., Catanzariti, R., Rio, D., Bolla, E.M. & Valvasoni, E. 2010. Mid-latitude calcareous nannofossil biostratigraphy, biochronology
and evolution across the Middle to Late Eocene transition. Stratigraphy, 7: 229–264.
Martini, E. 1971. Standard Tertiary and Quaternary calcareous nannoplankton zonation. In: A. Farinacci (Ed.). Proceedings II Planktonic Conference,
Rome, 1970. Tecnoscienza, 1: 738–785.
Murray, J.W. 1991. Ecology and paleoecology of benthic foraminifera. John Wiley and Sons, New York: 1–397.
Pearson, P.N., Ditchﬁeld, P.W., Singano, J., Harcourt-Brown, K.G., Nicholas, C.J., Olsson, R., Shackleton, N.J. & Hall, M.A. 2001. Warm tropical sea
surface temperatures in the Late Cretaceous and Eocene epochs. Nature, 413: 481–487.
Spofforth, D.J.A., Agnini, C., Pälike, H., Rio, D., Fornaciari, E., Giusberti, L., Luciani, V., Lanci, L. & Muttoni, G. 2010. Organic carbon burial
following the Middle Eocene climatic optimum in the central western Tethys. Paleoceanography, 25.
Toffanin, F., Agnini, C., Fornaciari, E., Rio, D., Giusberti, L., Luciani, V., Spofforth, D.J.A. & Pälike, H. 2011. Changes in calcareous nannofossil
assemblages during the Middle Eocene Climatic Optimum: Clues from the central western Tethys (Alano section, NE Italy). Marine
Micropaleontology, 81: 22–31.
Westerhold, T., Marwan, N., Drury, A.J., Liebrand, D., Agnini, C., Anagnostou, E., Barnet, J.S., Bohaty, S.M., De Vleeschouwer, D., Florindo, F.
& Frederichs, T. 2020. An astronomically dated record of Earth’s climate and its predictability over the last 66 million years. Science, 369:
1383–1387.

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